postgresql: change plugin id (#77444)

* postgres: change plugin id

* fixed cue file

* codeowners update

* fixed backend test

pkg/tsdb/grafana-postgresql-datasource/postgres_test.go

@@ -166,7 +166,7 @@ func TestIntegrationGenerateConnectionString(t *testing.T) {
 }
 
 // To run this test, set runPostgresTests=true
-// Or from the commandline: GRAFANA_TEST_DB=postgres go test -tags=integration -v ./pkg/tsdb/postgres
+// Or from the commandline: GRAFANA_TEST_DB=postgres go test -tags=integration -v ./pkg/tsdb/grafana-postgresql-datasource
 // The tests require a PostgreSQL db named grafanadstest and a user/password grafanatest/grafanatest!
 // Use the docker/blocks/postgres_tests/docker-compose.yaml to spin up a
 // preconfigured Postgres server suitable for running these tests.