Ignore exception when checking for cgroupsv2

[rschu1ze]

Fixes #64107

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[kssenii]

May be we should explicitly catch std::filesystem error and check for error code permission denied and only in this case return false and otherwise throw?

[rschu1ze]

You are right that catching ... is too coarse.

fs::filesystem::exists throws:

• std::filesystem::filesystem_error for "underlying API issues" (docs) e.g. wrong permissions. We should catch and ignore any of these without logging as most callers provide a fallback to cgroups v1.
• std::bad_alloc for OOMs and std::exception for everything else. We should let these simply bubble up.

[robot-ch-test-poll1]

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