[clang] [llvm] [clang][python][test] Move python binding tests to lit framework (PR #145855)

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dyung wrote:

Apologies @rorth, I've reverted your change in b0500f56c8b6b8dd21c4689cc6aa90d4d5ed7cfb to get the bot back to green. If you need some help testing a revised solution, please do let me know.

https://github.com/llvm/llvm-project/pull/145855