[clang] [clang][test] Rewrote test to work with lit internal shell syntax (PR #105902)

[Paul Kirth via cfe-commits]

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+import argparse
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ilovepi wrote:

@pogo59 You mentioned in the [RFC](https://discourse.llvm.org/t/rfc-enabling-the-lit-internal-shell-by-default/80179/29) that when there isn't another good option that a python script may be an OK substitute in some cases. I'm only aware of a couple of those in the tree(mostly in lit's own test directory). Do you know if these require a license header, or if we have a good convention for wether to use `#!/bin/env python` or not. 

https://github.com/llvm/llvm-project/pull/105902