Change the constructor and instance registers into a single
constructor_then_instance register, and add some register allocation
scopes to reduce temporary register use. This also allows us to change
FindNonDefaultConstructor to only need one output for both constructor
and instance.

Also make BuildCreateArrayLiteral a bit more friendly to the interpreter
register allocation.,

Bug: v8:13091
Change-Id: I0b6015b0bc6810bb4607157d715b7e536efb89f3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3876386Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83077}