EX-6807 tests: sync MDT for sanity-lipe-find3/109

EX-6807 tests: sync MDT for sanity-lipe-find3/109

Added sync all data to ensure that new created directory
flushed on MDT and lipe_scan3 works reliably
when scans inodes

Test-Parameters: trivial mdscount=2 mdtcount=4 ostcount=8 env=ONLY=109 testlist=sanity-lipe-find3
Test-Parameters: trivial testgroup=full-dne-part-2
Signed-off-by: Alexandre Ioffe <aioffe@ddn.com>
Change-Id: If0e8b7de024a1c8c7e1124173e9b3472ea8616b0
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/49860
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Colin Faber <cfaber@ddn.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>