EX-10036 tests: delay verification to finish set flag

EX-10036 tests: delay verification to finish set flag

- clean files in the pools before start of the test
to be focused only on set of test files
- reset changelog before lamigo starting to prevent lamigo
from normal synch work and be focused only on scan work
- Wait a bit until set flag commands finish before
verifying them

Test-Parameters: trivial testlist=hot-pools
Test-Parameters: trivial testlist=hot-pools env=ONLY="60 82",ONLY_REPEAT=10
Test-Parameters: trivial testlist=hot-pools env=ONLY="60 82",ONLY_REPEAT=10
Signed-off-by: Alexandre Ioffe <aioffe@ddn.com>
Change-Id: I70c5252564cfe6eeebb0cfc4f8383f263a233a71
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/55546
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>