CBG-4894: Consider local/remote tombstones in the default conflict resolver for ISGR

[gregns1]

CBG-4894

• Adds logic to have local or remote wins from the default resolver if the local or remote document is a tombstone
• This was a bug in 4.0.0 implementation and aligns with what CBL does
• I did think about making this change to blip tester client but topology tests do not seem to like this at all so if we want to make that change I feel it needs its separate ticket given the debugging effort involved to understand why this is happening

Pre-review checklist

• Removed debug logging (fmt.Print, log.Print, ...)
• Logging sensitive data? Make sure it's tagged (e.g. base.UD(docID), base.MD(dbName))
• Updated relevant information in the API specifications (such as endpoint descriptions, schemas, ...) in docs/api

Integration Tests

• GSI=true,xattrs=true https://jenkins.sgwdev.com/job/SyncGatewayIntegration/127/

[Copilot]

Pull Request Overview

This PR fixes a bug in the default conflict resolver for ISGR by adding logic to handle local or remote tombstones, aligning the behavior with Couchbase Lite. The change ensures that when one document is a tombstone and the other is not, the tombstone wins in the conflict resolution.

• Adds tombstone consideration logic to the default conflict resolver
• Removes outdated test comments related to CBG-4799
• Adds comprehensive test coverage for both local and remote tombstone scenarios

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
rest/replicatortest/replicator_test.go	Removes outdated comments about CBG-4799 refactoring
rest/replicatortest/replicator_conflict_test.go	Adds new test cases for default resolver with local and remote tombstones
db/hybrid_logical_vector.go	Implements the core logic to handle tombstones in conflict resolution

[torcolvin]

LGTM, I wonder if you want to look if we can shorten the boilerplate for the tests to make them easier to read and this is a good time in the release cycle to think about this.