Closes #46530.

Closes #32258.

This commit has two migrations:

1. The first prunes duplicate rows in the project_features table and leaves
   the row with the highest ID.  Since the behavior was indeterministic before
   and depended on which row the database decided to use, this change at least
   makes the permissions consistent. For example, in some cases, the Wiki may
   have been disabled but enabled in another entry.

2. The second adds a non-null constraint on the project_features.project_id
   column.

Closes #37882

Fixes a significant part of gitlab-com/migration#408.

We found that we were overcounting Wikis because of these duplicates.
On GitLab.com, there are 56 rows with duplicate entries by project_id, and 16,661 rows with NULL project_id values.

We use this to filter runner and will use this increasingly in future
instead of is_shared so it should be indexed

This will act as a cache, otherwise we would need to load the
`term_agreements` for a user on each request.

Using this field the result we're interested in is loaded when the
current user is loaded, without causing an extra query.

That way we can link a users acceptance of terms directly to a terms record.

Add a flag to applications settings to enforce users to accept terms
before using the GitLab instance

* processes any pending records which are not migrated yet
* bumps import_export version because of new commits_count attribute
* removes commits_count fallback method

Cleans merge request css