Make centos-9-stream job voting

bug#1960346 is fixed by the below series
- https://review.opendev.org/q/(topic:bug/1960346+OR+topic:wait_until_sshable_pingable)+status:merged
and now centos-9-stream job is passing and made voting
on tempest gate.

This commit makes devstack centos9 steam platform job
as voting and add it gate pipeline too.

Change-Id: Ic35420c5d58926ae90a136045a1558112accc533
1 file changed