Revert "grafana: skip a test that started failing"

This reverts commit cdefbd2eb0.
Let's fix the test instead.

pkgs/servers/monitoring/grafana/default.nix

@@ -48,9 +48,6 @@ buildGoModule rec {
     sed -i -e '/it should change folder successfully and return correct result/{N;s/$/\nt.Skip();/}'\
       pkg/services/libraryelements/libraryelements_patch_test.go
 
-    # TODO: investigate?
-    substituteInPlace pkg/tests/api/alerting/api_alertmanager_test.go \
-      --replace TestIntegrationAMConfigAccess DontTestIntegrationAMConfigAccess
 
     # main module (github.com/grafana/grafana) does not contain package github.com/grafana/grafana/scripts/go
     rm -r scripts/go