[GuardWidening] Fix widening possibility check (#66064)

In the 0e0ff857 was introduced
inconsistency between condition widening and checking if it's possible
to widen. We check the possibility to hoist checks parsed from the
condition, but hoist entire condition.

This patch returns testing that a condition can be hoisted rather than
the checks parsed from that condition.

Co-authored-by: Aleksander Popov <apopov@azul.com>