LU-16428 tests: cache is_project_quota_supported result

LU-16428 tests: cache is_project_quota_supported result

Rather than is_project_quota_supported() repeatedly checking if the
MDS supports project quota, check the MDS once after mount and then
cache it for the rest of the test run.

In resetquota() there is no need to check is_project_quota_supported()
each time, since this is only called with "-p" when project quota was
previously checked and is enabled.  Also, there is no need to wait 1s
after every quota limit is reset, but rather only once at the end.

Test-Parameters: trivial testlist=sanity-quota mdtcount=4 mdscount=2
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Id98240e2fcd2e862bb4305961a2946227e3ebbe5
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49499
Reviewed-by: Sergey Cheremencev <scherementsev@ddn.com>
Reviewed-by: Alex Deiter <alex.deiter@gmail.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>