Use lazy encoding in utf-8 encoded string comparison

[milaGGL]

The previous fix created a performance issue due to expensive UTF-8 encoding. Update compareUtf8Strings to use lazy encoding instead.

[github-actions]

Release note changes

The following release notes were modified. Please ensure they look correct.

Release Notes

firebase-firestore

### {{firestore}} version 25.1.3 {: #firestore_v25-1-3}

* {{fixed}} Use lazy encoding in UTF-8 encoded byte comparison for strings to solve performance issues. GitHub [#6706](//github.com/firebase/firebase-android-sdk/issues/6706){: .external}

* {{changed}} Updated `protolite-well-known-types` dependency to `18.0.1`. GitHub [#6716](//github.com/firebase/firebase-android-sdk/issues/6716){: .external}

#### {{firestore}} Kotlin extensions version 25.1.3 {: #firestore-ktx_v25-1-3}

The Kotlin extensions library transitively includes the updated
`firebase-firestore` library. The Kotlin extensions library has no additional
updates.

[google-oss-bot]

Coverage Report ¹

Affected Products

• firebase-firestore

  Overall coverage changed from 45.74% (ad7618b) to 45.76% (3aaa074) by +0.01%.

  Filename	Base (ad7618b)	Merge (3aaa074)	Diff
  DeleteMutation.java	95.24%	90.48%	-4.76%
  LruGarbageCollector.java	97.27%	93.64%	-3.64%
  SetMutation.java	94.44%	97.22%	+2.78%
  Util.java	73.94%	75.80%	+1.85%

Test Logs

• Base (ad7618b): https://github.com/firebase/firebase-android-sdk/actions/runs/13593668924
• Merge (3aaa074): https://github.com/firebase/firebase-android-sdk/actions/runs/13635395139

1. https://storage.googleapis.com/firebase-sdk-metric-reports/UyNhEzhE2m.html

[github-actions]

Test Results

  186 files   -   848    186 suites   - 848   4m 42s ⏱️ - 29m 31s
1 235 tests  - 4 656  1 219 ✅  - 4 650  16 💤  -  6  0 ❌ ±0 
2 494 runs   - 9 351  2 462 ✅  - 9 339  32 💤  - 12  0 ❌ ±0 

Results for commit 629b394. ± Comparison against base commit ad7618b.

This pull request removes 4657 and adds 1 tests. Note that renamed tests count towards both.

com.google.android.datatransport.cct.CctBackendFactoryTest ‑ create_returnCCTBackend_WhenBackendNameIsCCT
com.google.android.datatransport.cct.CctDestinationTest ‑ cctDestination_shouldOnlySupportProtoAndJson
com.google.android.datatransport.cct.CctDestinationTest ‑ cctDestination_shouldSupportProtoAndJson
com.google.android.datatransport.cct.CctTransportBackendTest ‑ decorate_whenOffline_shouldProperlyPopulateNetworkInfo
com.google.android.datatransport.cct.CctTransportBackendTest ‑ decorate_whenOnline_shouldProperlyPopulateNetworkInfo
com.google.android.datatransport.cct.CctTransportBackendTest ‑ schedule_shouldAddCookieOnPseudonymousIds
com.google.android.datatransport.cct.CctTransportBackendTest ‑ schedule_shouldDropCookieOnMixedPseudonymousIds
com.google.android.datatransport.cct.CctTransportBackendTest ‑ send_CompressedResponseIsUncompressed
com.google.android.datatransport.cct.CctTransportBackendTest ‑ send_whenBackendRedirectsMoreThan5Times_shouldOnlyRedirect4Times
com.google.android.datatransport.cct.CctTransportBackendTest ‑ send_whenBackendRedirects_shouldCorrectlyFollowTheRedirectViaPost
…

com.google.firebase.firestore.util.UtilTest ‑ compareUtf8StringsShouldReturnCorrectValue

♻️ This comment has been updated with latest results.

[google-oss-bot]

Size Report ¹

Affected Products

• firebase-firestore

  Type	Base (ad7618b)	Merge (3aaa074)	Diff
  aar	1.45 MB	1.45 MB	+315 B (+0.0%)
  apk (release)	11.4 MB	11.4 MB	+252 B (+0.0%)

Test Logs

• Base (ad7618b): https://github.com/firebase/firebase-android-sdk/actions/runs/13593668924
• Merge (3aaa074): https://github.com/firebase/firebase-android-sdk/actions/runs/13635395139

1. https://storage.googleapis.com/firebase-sdk-metric-reports/raKzI7Psoi.html