(diff better viewed ignoring whitespace)
In pytest<8, the collection tree for `pyargs` arguments in an invocation
like this:
pytest --collect-only --pyargs pyflakes.test.test_undefined_names
looked like this:
```
<Package test>
<Module test_undefined_names.py>
<UnitTestCase Test>
<TestCaseFunction test_annotationUndefined>
... snipped ...
```
The pytest 8 collection improvements changed it to this:
```
<Dir pytest>
<Dir .tox>
<Dir venv>
<Dir lib>
<Dir python3.11>
<Dir site-packages>
<Package pyflakes>
<Package test>
<Module test_undefined_names.py>
<UnitTestCase Test>
<TestCaseFunction test_annotationUndefined>
... snipped ...
```
Besides being egregious (and potentially even worse than the above,
going all the way to the root, for system-installed packages, as is
apparently common in CI), this also caused permission errors when trying
to probe some of those intermediate directories.
This change makes `--pyargs` arguments no longer try to add parent
directories to the collection tree according to the `--confcutdir` like
they're regular arguments. Instead, only add the parents that are in the
import path. This now looks like this:
```
<Package .tox/venv/lib/python3.11/site-packages/pyflakes>
<Package test>
<Module test_undefined_names.py>
<UnitTestCase Test>
<TestCaseFunction test_annotationUndefined>
... snipped ...
```
Fix#11904.
Ran Benita