In GitLab 9.0,
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9661 removed the
`subscribed` flag from the API when the user requested a list of issues
or merge requests since calculating this value triggers extensive
Markdown processing.

In GitLab 12.0 via a4fbf39e, we accidentally reintroduced this
performance regression by changing `IssueBasic` to `Issue` in
`entities.rb`. This showed up as a Gitaly N+1 issue since the Markdown
processing would attempt to extract a commit if it detected a regex that
matched a commit.

We restore the prior behavior by once again removing the `subscribed`
flag for the bulk list of issues and merge requests and add a test to
ensure they aren't reintroduced.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/66202

Remove label issue and MR counts from default API responses

See merge request gitlab-org/gitlab-ce!31543

As decided in https://gitlab.com/gitlab-org/gitlab-ce/issues/53593

These counts significantly increase the load time for these
requests. Users can now opt in to receiving the counts by setting
`with_counts=true` in requests. This is a breaking change, but hopefully
a fairly minor one.

`allow_local_requests_for_hooks_and_services` was renamed to
`allow_local_requests_for_web_hooks_and_services`.

Expose git blame in api

Closes #51345

See merge request gitlab-org/gitlab-ce!30675

These are not required because MySQL is not
supported anymore

None of this code can be reached any more, so it can all be removed