Revert "Repply#2 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)""

This reverts commit 91446e2a and
a unittest followup 1530f319 (#90476).

In a stage-2 -flto=thin -gsplit-dwarf -g -fdebug-info-for-profiling
-fprofile-sample-use= build of clang, a ThinLTO backend compile has
assertion failures:

    Global is external, but doesn't have external or weak linkage!
    ptr @_ZN5clang12ast_matchers8internal18makeAllOfCompositeINS_8QualTypeEEENS1_15BindableMatcherIT_EEN4llvm8ArrayRefIPKNS1_7MatcherIS5_EEEE
    function declaration may only have a unique !dbg attachment
    ptr @_ZN5clang12ast_matchers8internal18makeAllOfCompositeINS_8QualTypeEEENS1_15BindableMatcherIT_EEN4llvm8ArrayRefIPKNS1_7MatcherIS5_EEEE

The failures somehow go away if -fprofile-sample-use= is removed.