Build: clean up and document integration test convention (#58170)

* clean up and document integration test convention

* clarify integration test conventions

* clean up integration tests that don't follow convention

* mark testIntegration* functions as helpers to avoid confusion

pkg/services/preference/prefimpl/sqlx_store_test.go

@@ -7,6 +7,9 @@ import (
 )
 
 func TestIntegrationSQLxPreferencesDataAccess(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test")
+	}
 	testIntegrationPreferencesDataAccess(t, func(ss db.DB) store {
 		return &sqlxStore{sess: ss.GetSqlxSession()}
 	})