[InstCombine] Skip replaceExtractElements for ConstantData (#160575)
Closes https://github.com/llvm/llvm-project/issues/160507.
Note: Replacing other users except for `ExtElt` is a bit strange to me.
I tried to only replace `ExtElt` with a new extractelement, but it
caused regressions on `widen_extract2/3`.