Debug Buildbot Builders Should Run Galera Tests

The foundation buildbot doesn't run Galera MTR tests on a debug build.
This means patches can be pushed into the community MariaDB server
repository without running these debug tests, often resulting in code
pushed that breaks Galera. This is only ever found later by either the
Galera team manually running these tests, or the Enterprise CI pipeline.
In the case of the former, this often results in many test failures that
are only found just before a release.

The debug builders should be updated to run Galera tests to prevent such
problems. There are likely to be test failures off the bat from such a
change, which should be fixed before actually updating the builder. So
this change should require coordination with the Galera development team
to ensure these tests are fixed.