Update quickstart tests based on quickstart-ios/issues/1260

[paulb777]

The Unit/UI tests are currently failing in some of the quickstarts as documented in firebase/quickstart-ios#1260. The API of the quickstart test.sh has changed to require a TEST environment variable to disable the unit test run.

This PR makes the corresponding update for this repo.

#no-changelog

[morganchen12]

firebase/quickstart-ios#1260 to link the issues together

[google-oss-bot]

Coverage Report

Affected SDKs

• FirebaseAuth-iOS-FirebaseAuth.framework

  SDK overall coverage changed from 68.66% (4d51850) to 68.67% (b7e096c) by +0.01%.

  Filename	Base (4d51850)	Head (b7e096c)	Diff
  FIRAuthKeychainServices.m	59.38%	60.16%	+0.78%

• FirebaseFirestore-iOS-FirebaseFirestore.framework

  SDK overall coverage changed from 88.48% (4d51850) to 88.52% (b7e096c) by +0.04%.

  Filename	Base (4d51850)	Head (b7e096c)	Diff
  exception.cc	24.49%	75.51%	+51.02%
  exception_apple.mm	89.66%	58.62%	-31.03%
  leveldb_key.cc	98.25%	97.96%	-0.29%
  task.cc	97.60%	95.21%	-2.40%

• FirebaseMessaging-iOS-FirebaseMessaging.framework

  SDK overall coverage changed from 17.11% (4d51850) to 65.01% (b7e096c) by +47.90%.

  Click to show coverage changes in 24 files.

  Filename	Base (4d51850)	Head (b7e096c)	Diff
  FIRMessaging.m	10.00%	52.62%	+42.62%
  FIRMessagingAPNSInfo.m	0.00%	87.23%	+87.23%
  FIRMessagingAnalytics.m	0.00%	80.00%	+80.00%
  FIRMessagingAuthKeychain.m	38.76%	88.76%	+50.00%
  FIRMessagingAuthService.m	4.64%	93.04%	+88.41%
  FIRMessagingCheckinPreferences.m	60.91%	98.18%	+37.27%
  FIRMessagingCheckinService.m	6.27%	91.76%	+85.49%
  FIRMessagingCheckinStore.m	72.48%	83.22%	+10.74%
  FIRMessagingContextManagerService.m	0.00%	67.14%	+67.14%
  FIRMessagingExtensionHelper.m	0.00%	79.92%	+79.92%
  FIRMessagingKeychain.m	32.06%	93.89%	+61.83%
  FIRMessagingLogger.m	73.58%	100.00%	+26.42%
  FIRMessagingPendingTopicsList.m	2.52%	91.37%	+88.85%
  FIRMessagingPersistentSyncMessage.m	0.00%	38.10%	+38.10%
  FIRMessagingPubSub.m	10.93%	53.85%	+42.91%
  FIRMessagingRemoteNotificationsProxy.m	0.00%	73.64%	+73.64%
  FIRMessagingRmqManager.m	0.00%	58.57%	+58.57%
  FIRMessagingSyncMessageManager.m	19.23%	73.08%	+53.85%
  FIRMessagingTokenDeleteOperation.m	0.00%	9.64%	+9.64%
  FIRMessagingTokenInfo.m	41.06%	82.78%	+41.72%
  FIRMessagingTokenManager.m	4.12%	43.05%	+38.93%
  FIRMessagingTokenOperation.m	95.57%	96.84%	+1.27%
  FIRMessagingUtilities.m	54.42%	60.11%	+5.70%
  NSDictionary+FIRMessaging.m	0.00%	26.47%	+26.47%

Test Logs

• Base (4d518509): https://github.com/firebase/firebase-ios-sdk/actions/runs/1163272250
• Head (b7e096c0): https://github.com/firebase/firebase-ios-sdk/actions/runs/1163945754

[paulb777]

Database and Messaging failures are not quickstarts and unrelated to this PR.

[morganchen12]

LGTM on green CI; database test failure appears to be a flake. Messaging may be scripting-related.