LU-11058 tests: cleanup persistent checksum= in 77k

LU-11058 tests: cleanup persistent checksum= in 77k

this trivial patch let me pass 77k locally. can be used
till actual solution is landed

Test-Parameters: trivial
Change-Id: I5c4b4cd15d8e02dd96d918c07aacd184014ade0c
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/34035
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>