Fix two CI endpoints for MRs where the source project is deleted

app/controllers/projects/merge_requests_controller.rb

@@ -398,7 +398,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
 
       status ||= "preparing"
     else
-      ci_service = @merge_request.source_project.ci_service
+      ci_service = @merge_request.source_project.try(:ci_service)
       status = ci_service.commit_status(merge_request.diff_head_sha, merge_request.source_branch) if ci_service
 
       if ci_service.respond_to?(:commit_coverage)