ENG-5276: Add an site API for procedure site tasks to set the last committed
txnId and spHandle.
ENG-5276: Set the last committed spHandle even if the committed RW transaction
didn't do anything.
ENG-5276: CompleteTransactionTask should advance the last committed txnId and
spHandle on the site even if the site is rejoining, so that the next snapshot
will have the correct per-partition txnId.
ENG-5276: Don't update the last committed txnId and spHandle during the rejoin
stage of live rejoin. Otherwise the IDs will go forward, then backward and
forward again during replay.
Revert "ENG-5276: Don't update the last committed txnId and spHandle during the rejoin"

This reverts commit ca59985db8bff071d9dee37253d0a3cb0a02bea6.
Fix a bug in Site.UpdateCatalog().

It should really pass the last committed spHandle instead of the txnId to
ee.quiesce().
ENG-5276: Separate the last committed spHandle from the spHandle used for
snapshot digest.

The one used for snapshot digest will be updated even when the site is rejoining
and skipping the tasks. The last committed spHandle will only be updated on undo
log truncation.
ENG-5276: Addressing Izzy's comment with cosmetic changes.

- Add comment to Site.setSpHandleForSnapshotDigest()

- Remove txnId from Site.truncateUndoLog()'s signature
Merge pull request #867 from VoltDB/ENG-5276

ENG-5276: Update per-partition txnId during rejoin

r=izzy