Revert "[clang][AST] fix ast-print of `extern <lang>` with >=2 declarators" (#93912)

Reverts llvm/llvm-project#93131 because it broke some lldb tests on the
Fuchsia Clang toolchain builders.

https://ci.chromium.org/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8746482644341901905/infra