Revert new pass manager coro-split and coro-elide

This reverts
https://reviews.llvm.org/rG7125d66f9969605d886b5286780101a45b5bed67 and
https://reviews.llvm.org/rG00fec8004aca6588d8d695a2c3827c3754c380a0 due
to buildbot failures:
http://lab.llvm.org:8011/builders/clang-cmake-x86_64-sde-avx512-linux/builds/34004