test: honour -short in Docker-backed TestMain and cabana list-service fixture

TestMain scanned os.Args for a literal -test.short, but go test passes
-test.short=true, so beachcomber, conga, lagoon and lighthouse started a
Postgres container even under -short. Parse the flags and use
testing.Short() instead; skip cabana's newListService fixture under -short
like adminGorm already does.

modules/cabana/query_test.go

@@ -269,6 +269,9 @@ var (
 
 func newListService(t *testing.T) (*service, *gorm.DB) {
 	t.Helper()
+	if testing.Short() {
+		t.Skip("requires testcontainers postgres")
+	}
 	listPGOnce.Do(func() {
 		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
 		defer cancel()