[InstSimplify] make uses of isImpliedCondition more efficient (NFCI)

As suggested in the post-commit comments for 019d76196f79fcff3c148,
this makes the usage symmetric with the 'and' patterns and should
be more efficient.

GitOrigin-RevId: b63fc26d33e16698e015d5942b4065fbacf44909
1 file changed