[InstCombine] remove redundant tests

The first test in this file is duplicated exactly in and.ll -> test33.
We have commuted and vector variants there too.

The second test is a composite of 2 folds. The first fold is tested
independently in add.ll -> flip_and_mask (including vector variant).
After that transform fires, the IR is identical to the first transform.

llvm-svn: 302676