adopt forked squirrel supporting from UPDATE FROM (#19896)

Fork https://github.com/Masterminds/squirrel as https://github.com/lieut-data/squirrel with the following changes:
* https://github.com/Masterminds/squirrel/pull/256 supporting FROM clause to update builder (Postgres)
* Extension of above to support multiple FROM in UPDATE (Postgres)
* Support for multiple tables in UPDATE (MySQL)

This PR then leverages those changes to simplify a query that previously had to be coded by hand and duplicate for each of MySQL and Postgres.

go.mod

@@ -126,6 +126,8 @@ require (
 	gopkg.in/yaml.v2 v2.4.0
 )
 
+replace github.com/Masterminds/squirrel v1.5.2 => github.com/lieut-data/squirrel v1.5.4
+
 // Hack to prevent the willf/bitset module from being upgraded to 1.2.0.
 // They changed the module path from github.com/willf/bitset to
 // github.com/bits-and-blooms/bitset and a couple of dependent repos are yet