[InstCombine] clean up InsertRangeTest; NFCI

It's much less code and easier to read if we don't duplicate
everything between the 'Inside' and not 'Inside' cases.

As noted with the FIXME, the goal is to make this vector-friendly
in a follow-up patch.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280183 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed