Signed-off-by: NRémy Coutable <remy@rymai.me>

So we don't have to do it in CreateDeploymentService
Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11695#note_31322649

When a new deployment is created, this will trigger the invalidation on
the etag cache on the environment. This flow is now explicitly tested.

To make sure that we're accessing the same instance, so ending up
with `env.external` = `env.external_url` shall be fine.

to the external_url from persisted environment,
and make the other utility methods private as
we don't really need to use them outside of the job.

When getting the max member access for a group of users, we stored the results
in RequestStore. However, this will only return results for project members, so
anyone who wasn't a member of the project would be checked once at the start,
and then once for each comment they made. These queries are generally quite
fast, but no query is faster!

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

Add a scope to search for the projects that are starred by a certain user.

This partially reverts be25bbc4.
Signed-off-by: NRémy Coutable <remy@rymai.me>

This reverts commit c425f366, reversing
changes made to 82f6c0f5.
Signed-off-by: NRémy Coutable <remy@rymai.me>

Also introduce Ci::Variable#to_runner_variable to
build up the hash for runner.

Also update the document and add a changelog entry

It was broken, because we introduced a default namespace, which was not used by terminal methods.