The nightly matrix with an empty cache takes several hours to complete due to
the amount of jobs. This will effectively block the entire CI for the php
organization since there is an organization-wide limit of 20 jobs. Move the
cache buster job to Sunday to make it less likely for folks to fight with the
Nightly build for resources.
This PR removes most of the logic of nightly_matrix.php by converting
nightly.yml to a workflow_call, and invoking it multiple times for each branch
in a new root.yml workflow. The naming of the files is intentionally kept to
make the diff readable. They may still be renamed afterward.
Closes GH-16642
These files are usually only used on master, as the cron trigger runs on master.
However, workflow_dispatch does use the file from the triggered branch.
Furthermore, we're looking into migrating to a workflow_call trigger, which will
also run on the target branch. Backport these files now to make those changes
easier.
Tim Düsterhus