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

This caused assert:
llvm/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp:110:
void llvm::DwarfFile::addScopeVariable(LexicalScope *, DbgVariable *):
Assertion `Ret.second' failed.

See comments https://reviews.llvm.org/D144006#4656350.

This reverts commit 3b449bd4.