Remove unused remoteDocumentKeys()

[schmidt-sebastian]

This is not used and hence we don't need to add recovery logic.

Addresses #2755

[google-oss-bot]

Binary Size Report

Affected SDKs

• @firebase/firestore

  Type	Base (f9c6dde)	Head (a514a35)	Diff
  browser	249 kB	249 kB	-148 B (-0.1%)
  esm2017	194 kB	194 kB	-99 B (-0.1%)
  main	490 kB	490 kB	-232 B (-0.0%)
  module	247 kB	247 kB	-148 B (-0.1%)

• @firebase/firestore/memory

  Type	Base (f9c6dde)	Head (a514a35)	Diff
  browser	190 kB	190 kB	-148 B (-0.1%)
  esm2017	148 kB	148 kB	-99 B (-0.1%)
  main	367 kB	367 kB	-232 B (-0.1%)
  module	188 kB	188 kB	-148 B (-0.1%)

• firebase

  Type	Base (f9c6dde)	Head (a514a35)	Diff
  firebase-firestore.js	288 kB	288 kB	-147 B (-0.1%)
  firebase-firestore.memory.js	230 kB	230 kB	-147 B (-0.1%)
  firebase.js	822 kB	821 kB	-147 B (-0.0%)

Test Logs

• Base (f9c6ddec): https://github.com/firebase/firebase-js-sdk/actions/runs/98570568
• Head (a514a359): https://github.com/firebase/firebase-js-sdk/actions/runs/98581164