Firestore: Fix 'where indexeddb is not available' tests that were broken by persistence changes

[dconeybe]

The tests 'fails with code unimplemented' and 'falls back without requiring a wait for the promise' tests in indexeddb.test.ts were broken by #7404, which changed the way that "persistence" was tracked in the integration tests. These test failures were not noticed because they don't get executed by CI. This PR fixes the tests by providing a means to not explicitly specify a localCache in FirestoreSettings and instead use the implicit default, which is required by these tests.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 463cae8

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[google-oss-bot]

Size Report ¹

Affected Products

No changes between base commit (6674fad) and merge commit (e607f22).

Test Logs

• Base (6674fad): https://github.com/firebase/firebase-js-sdk/actions/runs/5465413984
• Merge (e607f22): https://github.com/firebase/firebase-js-sdk/actions/runs/5466596587

1. https://storage.googleapis.com/firebase-sdk-metric-reports/77BgzZEtBY.html

[google-oss-bot]

Size Analysis Report ¹

Affected Products

No changes between base commit (6674fad) and merge commit (387967c).

Test Logs

• Base (6674fad): https://github.com/firebase/firebase-js-sdk/actions/runs/5465413984
• Merge (387967c): https://github.com/firebase/firebase-js-sdk/actions/runs/5466601702

1. https://storage.googleapis.com/firebase-sdk-metric-reports/ff2Slk7zQD.html

[milaGGL]

LGTM.