gh-94814: Improve coverage of _PyCode_CreateLineArray (GH-94852)

The case where there are more than (1 << 15) lines was not covered.

I don't know if increasing test coverage requires a blurb -- let me know if it does.

Automerge-Triggered-By: GH:brandtbucher
(cherry picked from commit 582ae86b)

Co-authored-by: Michael Droettboom <mdboom@gmail.com>