Make updateCollation.php a bit less murderous for WMF databases:

Make updateCollation.php a bit less murderous for WMF databases:
* Don't run a COUNT(*) query on what's potentially the entire categorylinks table on enwiki (hundreds of millions of rows). Put it in a miser mode check
* Wait for DB replication to catch up before processing the next batch. Implemented LoadBalancer::waitAll() for this purpose, which should behave more nicely than wfWaitForSlaves()