Fix MountDisks failure on reserved/unmountable partitions

[rajchaurasia03]

Summary

MountDisks fails with "The volume at index '' does not have either a volume index nor label defined. A mount point cannot be assigned to a partition that does not have volume information associated." on any target disk that has a reserved/metadata partition without a mountable identity. This blocks the profile before the workload (e.g. FIO) ever runs.

Fix

Added an IsMountable(DiskVolume) guard and apply it alongside the existing access-path filter in
CreateMountPointsAsync. A volume is considered mountable only when it has the identity its
platform's mount operation actually requires:

• Windows — a volume index or a drive letter.
• Unix — a device path (e.g. /dev/sdc1).

Reserved/metadata partitions have none of these and are now skipped instead of being handed to the
disk manager. Real data volumes are unaffected and still get mounted exactly once.

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[rajchaurasia03]

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