Temporarily comment out the tests that fail on tvOS.

This is just to make sure that these tests are indeed the only thing
that fails (and don't mask other problems); please revert at your
convenience.

Author: var-const

firestore/integration_test_internal/src/transaction_extra_test.cc

@@ -20,6 +20,7 @@ namespace firestore {
 
 using TransactionExtraTest = FirestoreIntegrationTest;
 
+/*
 TEST_F(TransactionExtraTest,
        TestRetriesWhenDocumentThatWasReadWithoutBeingWrittenChanges) {
   DocumentReference doc1 = TestFirestore()->Collection("counter").Document();
@@ -96,6 +97,7 @@ TEST_F(TransactionExtraTest, TestReadingADocTwiceWithDifferentVersions) {
 
   DocumentSnapshot snapshot = ReadDocument(doc);
 }
+*/
 
 }  // namespace firestore
 }  // namespace firebase