ceph-*trigger jobs need reworking

Fundamentally, the GitHub Pull Request Builder plugin is problematic because it may build an unknown number of branches in response to a single push event. It's also unmaintained.

`ceph-dev-pipeline-trigger` uses the generic git trigger plugin, which is more predictable, and maintained.

Edit: this issue specifically refers to ceph.git and ceph-ci.git builds; not builds of other related projects.

Start by locating the ceph-dev-pipeline-trigger configuration and the ceph.git and ceph-ci.git build definitions. Compare how those jobs use the GitHub Pull Request Builder plugin with the generic git trigger plugin, then verify that the affected builds respond predictably to push events without changing builds for other related projects.

Written by the indexing model from the issue text.