Bump mypy-protobuf in sync_tensorflow script and improve generation scripts

[Avasam]

Extracted from #11696 but w/o bumping tensorflow in the script or metadata.toml.

• Bump mypy-protobuf to 3.6.0
• Removed redundant extra Ruff run (fixed separately by both the mypy-protobuf bump and Re-order ruff runs in pre-commit #11737 )
• Download and install protoc rather than relying on the system one. libprotoc 3.6.1 that's bundled with my Ubuntu WSL doesn't support explicit optionals.
• print protoc version
• Speedup downloads by downloading source code zip instead of cloning tensorflow repo. Especially on subsequent runs where the download is already cached by wget
• Cleanup (delete) the temp dir after work in it is complete
• Delete old _pb2.pyi files before generating new ones
• Made the tensorflow script look a lot more like the protobuf script
• some formatting

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉