Remove test that references `release_edit_page`

Removes a test that references the `release_edit_page` feature flag
which should have been removed as part of
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/20401

spec/controllers/projects/releases_controller_spec.rb

@@ -144,14 +144,6 @@ describe Projects::ReleasesController do
       end
     end
 
-    context 'when feature flag `release_edit_page` is disabled' do
-      before do
-        stub_feature_flags(release_edit_page: false)
-      end
-
-      it_behaves_like 'not found'
-    end
-
     context 'when release does not exist' do
       let!(:release) { }
       let(:tag) { 'non-existent-tag' }