Temporarily revert "[Attributor] Unify testing (=updates,...)"

This patch reverts the 2 patches below, as on most systems the disabled
tests actually pass and that causes most bots to be red, including
  http://green.lab.llvm.org/green/job/clang-stage1-RA/8541/
  http://green.lab.llvm.org/green/job/clang-stage1-cmake-RA-expensive/15646/
  http://lab.llvm.org:8011/builders/clang-ppc64le-linux-lnt/builds/23690
  http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/16751

* [Attributor] Disable three tests until the SCC update bug was fixed
  commit 2ae1a76c27295370d552f57352508b7af4dba791.

* [Attributor] Unify testing (=updates,prefixes,run configurations,...)
  2bcf5793e14577ed3c9f15a77a35179ae544fff4.

GitOrigin-RevId: 0c22cb0fd7c56dec4af7d5f4dbe189611a92c908
87 files changed