[Transforms] add phase ordering tests for min/max/abs; NFC
Test that instcombine and early-cse can cooperate
to reduce sequences of select patterns that are not
composed of the same underlying instructions.
There's a bug in EarlyCSE (PR41083), and we can test
how much a possible fix (D74285) may affect optimization.
(cherry picked from commit 0ad6e726ec7eee8ef14a89fa288d5a1420d96b1e)