LU-18528 test: wait for quota pool nr

LU-18528 test: wait for quota pool nr

In test_68 in sanity_quota, the number of the quota pool in QMT
could be delayed to update, then it should wait for its update.

Test-Parameters: trivial testlist=sanity-quota fstype=zfs env=ONLY=68,ONLY_REPEAT=50
Signed-off-by: Hongchao Zhang <hongchao@whamcloud.com>
Change-Id: I2e1964cf39a493d68ddd6463aaa28cf173951979
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58409
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Emoly Liu <emoly@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>