LU-12706 tests: sanity-quota_4a fix

LU-12706 tests: sanity-quota_4a fix

Don't set force_sync for OST0000 as we are
checking inode limit that is not affected
by the OST usage. Forced sync at OST0000
might take some time to be finished and break
the logic of a test case.

Createmany creates files in a directory on MDT0,
so don't sync all mdts, only MDT0.

Test-Parameters: testlist=sanity-quota env=ONLY=4a,ONLY_REPEAT=200
Fixes: b86c88383f ("LU-12706 tests: sanity-quota 4a sync timeout fix")
Signed-off-by: Sergey Cheremencev <scherementsev@ddn.com>
Change-Id: If411429d8a1e968ebd554242db4b47b0c9421bf6
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/57088
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>