cp/mv: suppress xattr ENOTSUP errors for optional preservation

[ChrisDryden]

If a filesystem is unable to modify xattr in files with specific flags in mv and cp it is supposed to silently fail and not throw an error. There is a GNU test that tests this behaviour that has been failing and this change should address all of the expectations of the tests.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)
Congrats! The gnu test tests/dd/nocache_eof is no longer failing!

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/cp/cp-mv-enotsup-xattr is no longer failing!

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/shuf/shuf-reservoir. tests/shuf/shuf-reservoir is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/sort/sort-stale-thread-mem. tests/sort/sort-stale-thread-mem is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/cp/cp-mv-enotsup-xattr is no longer failing!

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/shuf/shuf-reservoir. tests/shuf/shuf-reservoir is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/sort/sort-stale-thread-mem. tests/sort/sort-stale-thread-mem is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/cp/cp-mv-enotsup-xattr is no longer failing!

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/cp/cp-mv-enotsup-xattr is no longer failing!