Stop matching on legacy app label

From now on, only match on the annotations, instead of falling back to
legacy app label. This enables users to use the app label for other
purposes such as helm charts.

lib/gitlab/kubernetes.rb

@@ -37,15 +37,10 @@ module Gitlab
 
     # Filters an array of pods (as returned by the kubernetes API) by their project and environment
     def filter_by_project_environment(items, app, env)
-      pods = filter_by_annotation(items, {
+      filter_by_annotation(items, {
         'app.gitlab.com/app' => app,
         'app.gitlab.com/env' => env
       })
-      return pods unless pods.empty?
-
-      filter_by_label(items, {
-        'app' => env, # deprecated: replaced by app.gitlab.com/env
-      })
     end
 
     # Converts a pod (as returned by the kubernetes API) into a terminal

spec/lib/gitlab/kubernetes_spec.rb

@@ -59,16 +59,6 @@ describe Gitlab::Kubernetes do
   describe '#filter_by_project_environment' do
     let(:matching_pod) { kube_pod(environment_slug: 'production', project_slug: 'my-cool-app') }
 
-    it 'returns matching legacy env label' do
-      matching_pod['metadata']['annotations'].delete('app.gitlab.com/app')
-      matching_pod['metadata']['annotations'].delete('app.gitlab.com/env')
-      matching_pod['metadata']['labels']['app'] = 'production'
-      matching_items = [matching_pod]
-      items = matching_items + [kube_pod]
-
-      expect(filter_by_project_environment(items, 'my-cool-app', 'production')).to eq(matching_items)
-    end
-
     it 'returns matching env label' do
       matching_items = [matching_pod]
       items = matching_items + [kube_pod]