Investigate ReindexCollectionTest failures

This looks like it might be another example of commits not quite happening correctly, see
SOLR-11035. Problem is I can’t get it to fail locally after 2,000 iterations.

So I’m going to add a bit to the bandaid to allow tests to conditionally fail if the bandaid would have made it pass. That way we can positively detect that the bandaid is indeed the case rather than change code and hope.

This shouldn’t add any noise to the Jenkins lists, as the test won’t fail in cases where it didn’t before.

In case people wonder what the heck I’m doing.

BTW, if we ever really understand/fix the underlying cause, we should make the bandaid code fail and see, then remove it if so.