[IR] Don't match icmp+select as min/max (#205595)
Since some time, we canonicalize integer min/max as intrinsics. Remove
the detection of icmp+select as min/max from the pattern matchers. These
matchers were quite expensive but, due to canonicalization, were almost
never hit.
Test updates are largely canonicalization of the input to use intrinics
instead of icmp+select. (Manual work, we unfortunately don't have a tool
to canonicalize the test input.)
