LP#1846354: Adjust upgrade script for speed

LP#1846354: Adjust upgrade script for speed

This commit makes minor adjustments to the upgrade script to speed it up
in the face of larger data sets.

NOTE: The DO blocks that provided assertion tests during the the upgrade
have been commented out, as they primarily test that the preceding
insert did not break in some way that would have inserted data from the
wrong table into the intermediate staging tables.  They take a very long
time to run in some cases, but are left here for testers to enable in
order to confirm that they would pass in production.

Signed-off-by: Mike Rylander <mrylander@gmail.com>