Wait for 'Uninstall' when installing Prometheus

Prometheus is uninstallable so waiting won't see 'Install' at all.
We'll see 'Uninstall' instead.

qa/qa/page/project/operations/kubernetes/show.rb

@@ -28,12 +28,16 @@ module QA
               end
             end
 
-            def await_installed(application_name)
+            def await_installed(application_name, button_text: 'Installed')
               within(".js-cluster-application-row-#{application_name}") do
-                page.has_text?('Installed', wait: 300)
+                page.has_text?(button_text, wait: 300)
               end
             end
 
+            def await_uninstallable(application_name)
+              await_installed(application_name, button_text: 'Uninstall')
+            end
+
             def ingress_ip
               # We need to wait longer since it can take some time before the
               # ip address is assigned for the ingress controller

qa/qa/resource/kubernetes_cluster.rb

@@ -47,7 +47,7 @@ module QA
             page.install!(:runner) if @install_runner
 
             page.await_installed(:ingress) if @install_ingress
-            page.await_installed(:prometheus) if @install_prometheus
+            page.await_uninstallable(:prometheus) if @install_prometheus
             page.await_installed(:runner) if @install_runner
 
             if @install_ingress