This PR adds `tini` to the C++ interop client and server to make them responsive to SIGTERM.
Closes#34518
COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/34518 from gnossen:ssa_interop_server a762b27178
PiperOrigin-RevId: 610766377
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* Increase core logging verbosity
* Make repo URL injectable
* Apparently that's not allowed
* Use ipv4 in interop server
* Add CSDS to Python interop client
* Revert CI script change
* Scale back logging
* Move env variable to dockerfile
* And Python too