Don't override rerun task in wheel-test environment (rerun-io#6087)

### What
Having the task defined in two environments creates the annoying
behavior of:
```
$ pixi run rerun
? The task 'rerun' can be run in multiple environments.

Please select an environment to run the task in: ›
❯ default
  cpp
  py-docs
  wheel-test
```

We only used that task in one place in the wheel tests, so rename it to
be clear.

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using examples from latest `main` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6087?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6087?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/6087)
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.github/workflows/reusable_test_wheels.yml

@@ -172,7 +172,7 @@ jobs:
         run: |
           pixi run -e wheel-test python -m rerun --version
           pixi run -e wheel-test which rerun
-          pixi run -e wheel-test rerun --version
+          pixi run -e wheel-test rerun-from-path  --version
 
       - name: Run unit tests
         run: cd rerun_py/tests && pixi run -e wheel-test pytest -c ../pyproject.toml

pixi.toml

@@ -243,9 +243,10 @@ torch = ">=2.0.1"
 pip = ">=23"
 
 [feature.wheel-test.tasks]
-# In the wheel-test environment we want to use the wheel-installed `rerun` binary on the path.
-# This overrides the `rerun` task from the default env which otherwise executes via cargo.
-rerun = "rerun"
+# In the wheel-test environment we want to confirm the`rerun` binary on the path executes as expected.
+# However, since `rerun` is already its own task, we can't just `pixi run rerun`. This task lets us work
+# around that and executes `rerun` from the system shell within the context of the pixi environment.
+rerun-from-path = "rerun"
 
 # Run the Python tests.
 # Don't call this on CI - use `nox` to run tests on all supported Python versions instead.