Revert "[Clang] Mark this pointer in destructors dead_on_return (#166276)"
This reverts commit 278fd0553ef5834e005a048a6b480631f3fc1b38.
This was causing some buildbot failures in DSE:
1. https://lab.llvm.org/buildbot/#/builders/25/builds/15425
2. https://lab.llvm.org/buildbot/#/builders/24/builds/17304