Revert "[Attributor][NFC] Let AbstractAttribute be an IRPosition"

It seems this breaks the windows builds:
  http://lab.llvm.org:8011/builders/llvm-clang-win-x-aarch64/builds/7454/steps/build-llvm-project/logs/stdio

This reverts commit 6782635e90c11a4535e5b08212c8bbd3b3486f8d.

GitOrigin-RevId: ebdb89399499cfca56fbf98c5f97d892d5976237
1 file changed