Remove duplicate test run (#3459)

Author: schmidt-sebastian

scripts/emulator-testing/firestore-test-runner.ts

@@ -48,8 +48,9 @@ async function run(): Promise<void> {
   try {
     await emulator.download();
     await emulator.setUp();
+    // When persistence is enabled, the test runner runs all tests
+    // twice (once with and once without persistence).
     await runTest(emulator.port, emulator.projectId, true);
-    await runTest(emulator.port, emulator.projectId, false);
   } finally {
     await emulator.tearDown();
   }