LU-17251 tests: increase parallel-scale OST seq_width

LU-17251 tests: increase parallel-scale OST seq_width

Increase seq_width earlier in parallel-scale so that OST SEQ rollover
does not happen during later testing (in particular test_rr_alloc).

Otherwise, the OST SEQ rollover can stall OST object preallocation
during the testing and provide skewed creation rates across OSTs.

Fix parallel-scale.sh so only tests which use MPI check MPI_USER.

Test-Parameters: trivial
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Test-Parameters: testlist=parallel-scale env=ONLY=statahead+rr_alloc
Fixes: 11d55259ab ("LU-17251 tests: try to fix test_rr_alloc again")
Fixes: 66d93ce3e4 ("LU-17251 test: improve parallel-scale rr_alloc test")
Fixes: 0ecb2a167c ("LU-11912 ofd: reduce LUSTRE_DATA_SEQ_MAX_WIDTH")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I79b146fff96dcc3c607e73bbb575c526d02540e5
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/57181
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>