[lldb][Type Completion] Fix various redecl-completion issues that stem from the UseRedeclCompletion setting split#8659

Michael137 merged 5 commits intoswiftlang:stable/20230725swiftlang/llvm-project:stable/20230725from

Michael137:bugfix/lldb/type-completion/crash-fixesMichael137/llvm-project:bugfix/lldb/type-completion/crash-fixesCopy head branch name to clipboard