What this PR does:
Inside ring module, there is logic to check conflict/duplicated tokens and resolve the conflict. However, during race condition that two instances joined the ring at same time, this logic will not detect conflicts during the first CAS cycle because none of new instances appeared in the ring. On the following CAS calls, none of those instance would do conflict check again because it did not detect any token changed.

Also, there was another issue in the original code. The issue was that even resolve token function made the correct operation. Token from instances that were not detected as newly added or updated will not be updated with new tokens even they have conflicts.

This change fixs both issues in the code. With the fix, each CAS call would do conflict check. It takes O(n*m) where n is number of instances in ring and m is number of tokens per instance. So the check should not add too much overhead for each CAS call. Also, add logic to make sure all instances got updated token during resolving conflict process would be properly updated. And this update should be idempotent to avoid updates around the same time produce the same result.

Which issue(s) this PR fixes:
NA

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]
• docs/configuration/v1-guarantees.md updated if this PR introduces experimental flags