Blocker Description
A little bit of follow up work is necessary as part of PHOENIX-4130. It looks like the partial index rebuilder writes (UngroupedAggregateRegionObserver.rebuildIndices()) do not have the new retry logic that's necessary. It's somewhat unfortunate that the logic isn't shared between the commits that happen in the loop of UngroupedAggregateRegionObserver.doPostScannerOpen() and rebuildIndices() as it'd be almost identical (except we know that all writes will be local writes).