Revert "[DebugMetadata][DwarfDebug] Support function-local types in lexical block scopes (4/7)"

This caused asserts:

  llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp:2331:
  virtual void llvm::DwarfDebug::endFunctionImpl(const llvm::MachineFunction *):
  Assertion `LScopes.getAbstractScopesList().size() == NumAbstractSubprograms &&
  "getOrCreateAbstractScope() inserted an abstract subprogram scope"' failed.

See comment on the code review for reproducer.

> RFC https://discourse.llvm.org/t/rfc-dwarfdebug-fix-and-improve-handling-imported-entities-types-and-static-local-in-subprogram-and-lexical-block-scopes/68544
>
> Similar to imported declarations, the patch tracks function-local types in
> DISubprogram's 'retainedNodes' field. DwarfDebug is adjusted in accordance with
> the aforementioned metadata change and provided a support of function-local
> types scoped within a lexical block.
>
> The patch assumes that DICompileUnit's 'enums field' no longer tracks local
> types and DwarfDebug would assert if any locally-scoped types get placed there.
>
> Reviewed By: jmmartinez
>
> Differential Revision: https://reviews.llvm.org/D144006

This reverts commit f8aab289.