This is a step for #29118.

Add a single metric to count successful logins.

Summary types are not supported so remove Collector.  Either
we need to support the summary type or we need to create a
multiprocess-friendly Collector.

Add config to load prometheus and set up the Collector and the
Exporter.

Fix `Gemfile` as current prometheus-client gemspec is missing the
`mmap2` dependency.

To avoid the use of slow queries, remove some deprecated methods and encourage
the use of ProjectFinder to find projects.

There was a race condition issue when the application was generating an
email and was using a language that was previously being used in other
request.

[ci skip]

* implemented logging of project and system web hooks
* implemented UI for user area (project hooks)
* implemented UI for admin area (system hooks)
* implemented retry of logged webhook
* NOT imeplemented log remover

This reverts commit b0498c17

compatible urls, which were for javascripts

For the index view, the environments can now be requested every 15
seconds. Any transition state of a projects environments will trigger a
cache invalidation action.

Fixes gitlab-org/gitlab-ce#31701

In order to avoid string manipulation or modify route params (to make them unambiguous for `url_for`), we are accepting a behavior change:

When being redirected to the canonical path for a group, if you requested a group show path starting with `/groups/…` then you’ll now be redirected to the group at root `/…`.

Don’t replace a substring of the path if it is part of the top level route.

E.g. When redirecting from `/groups/ups` to `/groups/foo`, be careful not to do `/grofoo/ups`.

Projects are unaffected by this issue, but I am grouping the `#ensure_canonical_path` tests similar to the group and user tests.

The host should not be modified, nor is it needed for the redirect.

This hides/disables some UI elements and API parameters related to
nested groups when MySQL is used, since nested groups are not supported
for MySQL.

Rename other URL generators

admin_builds_path -> admin_jobs_path

Fix tests and more renaming

Fix more tests

Also change build_id to job_id in the controller

[ci skip]

Fixes gitlab-org/gitlab-ce#30814

[ci skip]