[PWGHF] taskFlow.cxx : add more cuts on MFT tracks, add centrality, add dedicated process function for efficiencies

[AlexianL]

No description provided.

[github-actions]

O2 linter results: ❌ 0 errors, ⚠️ 0 warnings, 🔕 0 disabled

[alibuild]

Error while checking build/O2Physics/code-check for e718558 at 2026-07-24 23:03:

## sw/BUILD/O2Physics-code-check-latest/log
--
========== List of issues found ==========
++ echo 'Found 39 errors and 0 warnings.'
Found 39 errors and 0 warnings.
++ [[ 39 -gt 0 ]]
++ cat /sw/BUILD/d49d8691f9eb531629b9d149380463b2495e2c9f/O2Physics-code-check/errors.txt
PWGHF/HFC/Tasks/taskFlow.cxx:30:1: error: included header fwdtrackUtilities.h is not used directly [misc-include-cleaner,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:181:18: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:182:18: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:183:18: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:184:18: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:185:18: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:200:18: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:290:59: error: do not implicitly decay an array into a pointer; consider using gsl::array_view or an explicit cast instead [cppcoreguidelines-pro-bounds-array-to-pointer-decay,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:348:35: error: initializer for member 'cstFT0RelGain' is redundant [readability-redundant-member-init,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:511:5: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:523:5: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:541:5: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:591:5: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:601:5: error: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1004:47: error: the parameter 'collision' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1224:60: error: redundant boolean literal supplied to boolean operator [readability-simplify-boolean-expr,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1231:60: error: redundant boolean literal supplied to boolean operator [readability-simplify-boolean-expr,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1238:60: error: redundant boolean literal supplied to boolean operator [readability-simplify-boolean-expr,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1245:58: error: redundant boolean literal supplied to boolean operator [readability-simplify-boolean-expr,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1296:43: error: the parameter 'tracks' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1323:23: error: narrowing conversion from 'float' to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1605:23: error: narrowing conversion from 'Double_t' (aka 'double') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1738:15: error: Variable 'rad' with floating point type 'double' should not be used as a loop counter [clang-analyzer-security.FloatLoopCounter,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:1842:23: error: narrowing conversion from 'Double_t' (aka 'double') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:2041:23: error: narrowing conversion from 'Double_t' (aka 'double') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:2302:23: error: narrowing conversion from 'Double_t' (aka 'double') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:2446:23: error: narrowing conversion from 'Double_t' (aka 'double') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:2506:23: error: narrowing conversion from 'Double_t' (aka 'double') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:2636:9: error: do not use 'else' after 'return' [readability-else-after-return,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:2698:9: error: do not use 'else' after 'return' [readability-else-after-return,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:2762:9: error: do not use 'else' after 'return' [readability-else-after-return,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:2833:9: error: do not use 'else' after 'return' [readability-else-after-return,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:2925:9: error: do not use 'else' after 'return' [readability-else-after-return,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:3233:22: error: narrowing conversion from 'double' to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:4173:22: error: narrowing conversion from 'unwrap_t<float>' (aka 'float') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:4565:24: error: narrowing conversion from 'unwrap_t<float>' (aka 'float') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:4595:34: error: narrowing conversion from 'unwrap_t<float>' (aka 'float') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:4596:34: error: narrowing conversion from 'unwrap_t<float>' (aka 'float') to 'int' [bugprone-narrowing-conversions,-warnings-as-errors]
PWGHF/HFC/Tasks/taskFlow.cxx:4670:15: error: boolean expression can be simplified by DeMorgan's theorem [readability-simplify-boolean-expr,-warnings-as-errors]
++ [[ 0 -gt 0 ]]
++ [[ 39 -gt 0 ]]
++ exit 1
[0 more errors; see full log]

Full log here.