Disable most builds for auto-deploy branches and tags

When an auto-deploy branch gets updated we still build packages for distributions we ourselves don't run. And since we never make these packages available to the public, I think we're just wasting resources and bandwidth.

See https://dev.gitlab.org/gitlab/omnibus-gitlab/-/commit/afc537ee7dac5a34398942dc122c676e27202f09/pipelines?ref=12.10.202003242245%2Ba316b39d106.afc537ee7da for example.

The pipeline for the tag at https://dev.gitlab.org/gitlab/omnibus-gitlab/pipelines/148715 produces the packages we deploy to staging through production.

The pipeline on the branch at https://dev.gitlab.org/gitlab/omnibus-gitlab/pipelines/148714 just burns money as far as I can tell.