This suite was introduced to test the `getvxattr` op for newer clients with
older MDSs. There was a bug where the MDS would crash when a newer client
would send a `getvxattr` op(which the MDS did not understand). Then,
subsequently, we added more test to this under PR #48280 which added tests
to start from pacific and upgrade to reef since reef was the latest release
at that moment.

This suite should be testing what has been released (or close to being
released) and verify that a newer client (say on `main`) can talk to a
N-1|N-2 MDS.
