chore(firebaseai): setup for mock response e2e test #2351

Job	Run time
web-app-check	2m 56s
web (tests)	5m 7s
web-wasm (tests)	6m 17s
web (packages/cloud_firestore/cloud_firestore/example)	3m 48s
web-wasm (packages/cloud_firestore/cloud_firestore/example)	3m 22s
	21m 30s

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