[InstCombine] Lower infinite combine loop detection thresholds

Summary:
1000 iteratons is still kinda a lot.
Would it make sense to iteratively lower it, until it becomes `2`,
with some delay inbetween in order to let users actually potentially encounter it?

Reviewers: spatel, nikic, kuhar

Reviewed By: nikic

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D83160