After switching to ProxySQL as default we see following logs:
CRITICAL neutron [None req-c214fdae-5da7-402d-92b0-0572c278a5b5 - - - - - -] Unhandled error: sqlalchemy.exc.OperationalError: (pymysql.err.OperationalError) (9001, 'Max connect timeout reached while reaching hostgroup 0 after 10150ms')

Mainly in upgrade jobs, which otherwise pass successfuly - just fail on this
check.

Change-Id: I4336ec62a0a2dfbe815842f1bacb02135bcf4c0e