metrics: add delivery_packages_tagging_total

What does this MR do?

This is the first step in gitlab-com/gl-infra/delivery#1964 (closed)

We are adding delivery_packages_tagging_total with a pkg_type label to delivery-metrics.

Each time we tag a coordinated pipeline, we will increment the counter setting pkg_type=auto_deploy.

In release-tools this is controlled by the track_pkg_tagging feature flag