bd7ce05f9d test: fix `TestShell` initialization (late follow-up for #30463) (Sebastian Falbesoner)
Pull request description:
Creating a `TestShell` instance as stated in the [docs](https://github.com/bitcoin/bitcoin/blob/master/test/functional/test-shell.md) currently fails on master:
```
$ python3
Python 3.10.13 (main, Mar 15 2024, 07:36:23) [Clang 16.0.6 ] on openbsd7
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.path.insert(0, "/home/thestack/bitcoin/test/functional")
>>> from test_framework.test_shell import TestShell
>>> test = TestShell().setup(num_nodes=2, setup_clean_chain=True)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/thestack/bitcoin/test/functional/test_framework/test_shell.py", line 70, in __new__
TestShell.instance = TestShell.__TestShell()
TypeError: BitcoinTestFramework.__init__() missing 1 required positional argument: 'test_file'
```
Since #30463, BitcoinTestFramework instances expect the path of the calling test at construction, in order to find shared data like the configuration (config.ini) and the cache. Note that in contrast to actual functional tests, we can't simply pass `__file__` here, as the test shell module sits within the `test_framework` subfolder, so we have to navigate up to the parent directory and append some dummy test file name.
On the long-term we should probably add some TestShell instantation smoke-test to detect issues like this early. As I'm not too familiar with the CI I'm not sure what is a good way to achieve this (a functional test obviously can't be used, as that's already a BitcoinTestFramework test in itself), but happy to take suggestions.
ACKs for top commit:
ismaelsadeeq:
Tested ACK bd7ce05f9d
danielabrozzoni:
tACK bd7ce05f9d
brunoerg:
ACK bd7ce05f9d
Tree-SHA512: c3a2365e2cda48a233ee724673c490787981354914f33e10eadbbad9c68e8403d84c5551229a611401e743886539de380ba4bfcb77032b6c85731e3bbe962dc1