Eliminate N+1 queries in loading namespaces for every issuable in milestones
If we rely on the helper functions in GitlabRoutingHelper
for merge_request_path
,
we end up calling a database query to look up the Namespace association for
every merge request since entity.project.namespace
is called. By reusing the project
defined in the controller, we avoid that problem.
Partial fix to #27387 (closed)