These changes are squashed together to simplify applying them to config
management without zuul and ansible running one of these without the
others. We essentially need them all in place at the same time to
accurately reflect the post upgrade state.
We stop blocking /p/ in gerrit's apache vhost. /p/ is used for
dashboards.
We add a few java options that new gerrit sets by default.
We update the gerrit image in docker compose to 3.2.
We update zuul to use basic auth instead of digest auth when talking to
Gerrit.
Change-Id: I6ea38313544ce1ecbc4cfd914b1f33e77d0d2d03