Replace remaining calls to testing.Short where possible. (#110765)

* Replace remaining calls to testing.Short where possible.
* Update style guide.
* Revert change in TestAlertmanager_ExtraDedupStage, as it doesn't work.
* Make TestAlertRulePostExport into integration test.

pkg/tests/api/alerting/api_ruler_test.go

@@ -711,7 +711,7 @@ func TestIntegrationAlertRuleNestedPermissions(t *testing.T) {
 	})
 }
 
-func TestAlertRulePostExport(t *testing.T) {
+func TestIntegrationAlertRulePostExport(t *testing.T) {
 	testinfra.SQLiteIntegrationTest(t)
 
 	// Setup Grafana and its Database