LU-11975 test: fix for llog test 10h

LU-11975 test: fix for llog test 10h

At test 10h thread should set failloc before the test
starts adding records. And the main llog_process_thread
should wait a bitmap modification.

Signed-off-by: Alexander Boyko <c17825@cray.com>
Change-Id: I4fdedf10f943f6ab264c2d83414f0a404ca42b9c
Reviewed-on: https://review.whamcloud.com/34287
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>