LU-17919 tests: wait to resolve ENOSPC in sanity 398l

LU-17919 tests: wait to resolve ENOSPC in sanity 398l

Test 398l does not wait to clear up the ENOSPC it induces,
so sometimes it causes 398m to fail with ENOSPC.

Wait for deletes to resolve this.

OCI-bug-id: LFS-288

Note on test-parameters - we can't 'REPEAT' a pair of
tests, it would run 398l over and over and then 398m,
which doesn't test what we need to test.  So instead we
just create 5 sessions like this.

Test-Parameters: testlist=sanity envdefinitions=ONLY="398l 398m"
Test-Parameters: testlist=sanity envdefinitions=ONLY="398l 398m"
Test-Parameters: testlist=sanity envdefinitions=ONLY="398l 398m"
Test-Parameters: testlist=sanity envdefinitions=ONLY="398l 398m"
Test-Parameters: testlist=sanity envdefinitions=ONLY="398l 398m"
Test-Parameters: trivial
Signed-off-by: Patrick Farrell <patrick.farrell@oracle.com>
Change-Id: I2fcc1069a0304bc6edfa576331b6255289b71b98
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55359
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>