Fix revocation in reconcilation logic

Looks like there is a problem in the reconciliation logic.

We are getting 6 partitions from an HB, we add them to assignmentReadyToReconcile. Next HB we get only 4 partitions (2 are revoked), we also add them to assignmentReadyToReconcile, but the 2 partitions that were supposed to be removed from the assignment are never removed because they are still in assignmentReadyToReconcile.

This was discovered during integration testing of https://github.com/apache/kafka/pull/14878 - part of the test testRemoteAssignorRange was disabled and should be re-enabled once this is fixed.