postgresql: change plugin id (#77444)

* postgres: change plugin id

* fixed cue file

* codeowners update

* fixed backend test

pkg/plugins/plugins.go

@@ -137,6 +137,8 @@ func ReadPluginJSON(reader io.Reader) (JSONData, error) {
 		fallthrough
 	case "grafana-testdata-datasource":
 		fallthrough
+	case "grafana-postgresql-datasource":
+		fallthrough
 	case "annolist":
 		fallthrough
 	case "debug":