ci: turn gating back on for most testsuites

ci: turn gating back on for most testsuites

Somehow, this slipped through in #1513. We weren't inheriting anymore,
so `branches` defaulted back to just `master`. This means we weren't
gating on most of the containerized builds anymore. Ouch!

It'd make sense to teach PAPR to allow some defaults across all
testsuites, even in the `inherit: false` case. Though it's tempting to
also just change the hardcoded PAPR default to those branches since our
use of Homu + PAPR at this point is pretty ubiquitous, and it doesn't
really hurt for the ones that don't use it.

Closes: #1536
Approved by: cgwalters