LU-17567 tests: improve sanity.sh:test_27T

LU-17567 tests: improve sanity.sh:test_27T

sanity.sh:test_27T is to take care that second of write rpcs generated
by multiop fails with ENOSPC. Otherwise, grant accounting breaks.

Test-Parameters: testlist=sanity env=ONLY="27T 42d"
HPE-bug-id: LUS-11178
Signed-off-by: Vladimir Saveliev <vladimir.saveliev@hpe.com>
Change-Id: I056145ffc223f943585edbaa70f92ab9d5fdc1f1
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/54113
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Nikitas Angelinas <nikitas.angelinas@hpe.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>