[libc++][NFC] Use _LIBCPP_DEBUG_ASSERT in <__hash_table>

Use `_LIBCPP_DEBUG_ASSERT` in `<__hash_table>`

Reviewed By: Quuxplusone, ldionne, Mordante, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D116486

NOKEYCHECK=True
GitOrigin-RevId: 875dd75e5ab45fc48d12cdbad4fc0aa228abe6b5
1 file changed