[Firestore] Follow-up review items from #11954 #5968

Job	Run time
changes	5s
spm-binary-cron	0s
check	4m 11s
xcodebuild (iOS)	43m 24s
cmake (macos-12)	18m 54s
xcodebuild (tvOS)	16m 48s
cmake (ubuntu-latest)	3m 21s
xcodebuild (macOS)	39m 42s
cmake-prod-db (macos-12, (default))	33m 46s
sanitizers (macos-12, asan)	26m 27s
cmake-prod-db (macos-12, test-db)	34m 8s
sanitizers (macos-12, tsan)	41m 18s
pod-lib-lint (FirebaseFirestoreInternal.podspec)	33m 8s
pod-lib-lint (FirebaseFirestore.podspec)	35m 13s
spm-binary	4m 3s
pod-lib-lint-cron	0s
pod-lib-lint (FirebaseFirestoreSwift.podspec)	33m 37s
spm-source	21m 40s
Check all required Firestore tests results	1s
	6h 29m 46s

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