Remove support for Google Spanner database. (#105846)

* Remove support for Google Spanner database.

pkg/services/annotations/annotationsimpl/annotations_test.go

@@ -203,10 +203,6 @@ func TestIntegrationAnnotationListingWithInheritedRBAC(t *testing.T) {
 		t.Skip("skipping integration test")
 	}
 
-	if db.IsTestDBSpanner() {
-		t.Skip("skipping integration test")
-	}
-
 	orgID := int64(1)
 	permissions := []accesscontrol.Permission{
 		{

pkg/services/annotations/annotationsimpl/xorm_store.go

@@ -334,7 +334,6 @@ func (r *xormRepositoryImpl) Get(ctx context.Context, query annotations.ItemQuer
 			}
 
 			if len(tags) > 0 {
-				// "at" is a keyword in Spanner and needs to be quoted.
 				tagsSubQuery := fmt.Sprintf(`
 			SELECT SUM(1) FROM annotation_tag `+r.db.Quote("at")+`
 			INNER JOIN tag on tag.id = `+r.db.Quote("at")+`.tag_id