Setuptools was updated and our hacky namespace-package-chickens came
back to roost. This removes the unsupported namespace package hacks.

Increase test timeout of testMetadata to 8s to alleviate flakiness under overloaded Jenkins mac machine

a real core shutdown of a CQ until such requests are done

GPR Buffers need to be destroyed, not directly freed, otherwise it leaks reference counted backing slices.