LU-14682 tests: sanity-flr to remove temporary files

LU-14682 tests: sanity-flr to remove temporary files

otherwise the test fails frequently on small local systems due
to lack of space.

Test-Parameters: trivial testlist=sanity-flr
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I7076bcf2346ae1ec7a4d1bead3d94b2c4bb57bbf
Reviewed-on: https://review.whamcloud.com/43669
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>