Bug 1907949

Description of problem:
Seen during an FFU where we upgrade mariadb to 10.3.27 which is scheduled to be released in RHEL due to CVE fixes and some SST fixes (https://bugzilla.redhat.com/show_bug.cgi?id=1899022 amongst others)

The FFU will fail on the first controller with:
[root@controller-0 stdouts]# more nova_db_sync.log
2020-12-14T11:54:54.186418426+00:00 stdout F ERROR: Could not access cell0.
2020-12-14T11:54:54.186418426+00:00 stdout F Has the nova_api database been created?
2020-12-14T11:54:54.186418426+00:00 stdout F Has the nova_cell0 database been created?
2020-12-14T11:54:54.186418426+00:00 stdout F Has "nova-manage api_db sync" been run?
2020-12-14T11:54:54.186418426+00:00 stdout F Has "nova-manage cell_v2 map_cell0" been run?
2020-12-14T11:54:54.186418426+00:00 stdout F Is [api_database]/connection set in nova.conf?
2020-12-14T11:54:54.186418426+00:00 stdout F Is the cell0 database connection URL correct?
2020-12-14T11:54:54.186418426+00:00 stdout F Error: (pymysql.err.InternalError) (1118, 'Row size too large.
The maximum row size for the used table type, not counting BLOBs, is 8126. This includes storage overhead, c
heck the manual.
 You have to change some columns to TEXT or BLOBs')
2020-12-14T11:54:54.186418426+00:00 stdout F [SQL:
2020-12-14T11:54:54.186418426+00:00 stdout F ALTER TABLE instances ADD hidden BOOL]
2020-12-14T11:54:54.186418426+00:00 stdout F (Background on this error at: http://sqlalche.me/e/2j85)