EX-7342 test: remove extra cleanup and qp check

EX-7342 test: remove extra cleanup and qp check

The test_79 in sanity-quota needs quota pool support, and
the cleanup of the "stop file" is also included in the
stack_trap, then it is no need to to do it explicitly.

Test-Parameters: trivial
Signed-off-by: Hongchao Zhang <hongchao@whamcloud.com>
Change-Id: If86a1d0187b4b95d0c5e24f11f5f058280726e64
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52472
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>