[x86] Just delete the last combine test file.

This file isn't really doing anything useful. Many of the tests that
seem to be combined are also repeats from other test files. Many of the
other tests, despite the comment that they should be combined into
a single shuffle... well... aren't combined into a single shuffle.
=/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218862 91177308-0d34-0410-b5e6-96231b3b80d8