The test method deleteLiveReplicaTest actually belongs to the parent class DeleteReplicaTest.
I think started happening after
SOLR-6902. The DeleteInactiveReplicaTest extends the DeleteReplicaTest and used to override the doTest method. After SOLR-6902 we started using annotations and now the test methods in the parent class are also executed as part of this test. But the parent sets sliceCount=2 and sets checkCreatedVsState flag to false which DeleteInactiveReplicaTest doesn't and hence the odd failure.
I'll fix by not inheriting from that class. There's just two methods being shared and they can easily be made package private. A cleanup of these cloud tests is due but that will need it's own issue.