Remove config overrides for rummager CI builds
Remove config overrides for rummager CI builds

Delete the configuration which specifies which rummager branches are
built by Jenkins, so that the default config is used. This change means
that the rummager `deployed-to-production` branch will no longer be
built by Jenkins.

The default config includes all `deployed-to-X` branches. We had wanted
to override this so that Jenkins would build the
`deployed-to-production` branch so that rummager's production code could
be tested against content schema changes, but rummager doesn't actually
depend directly on the content schemas, so this was unnecessary.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet