Alerting: Omit "description" and "summary" from default email template annotations (#68122) (#68189)

* Alerting: Omit "description" and "summary" from default email template annotations (#68122)

(cherry picked from commit 720b5b3b65)

Co-authored-by: Matthew Jacobson <matthew.jacobson@grafana.com>

pkg/services/ngalert/notifier/email_test.go

@@ -112,11 +112,11 @@ func TestEmailNotifierIntegration(t *testing.T) {
 			expSnippets: []string{
 				"2 firing instances",
 				"<strong>severity</strong>",
-				"warning\n",
-				"critical\n",
+				"warning",
+				"critical",
 				"<strong>alertname</strong>",
-				"FiringTwo\n",
-				"FiringOne\n",
+				"FiringTwo",
+				"FiringOne",
 				"<a href=\"http://fix.me\"",
 				"<a href=\"http://localhost/base/d/abc",
 				"<a href=\"http://localhost/base/d/abc?viewPanel=5",