[BUG] pytest breaks in git worktrees due to misconfigured repository

## Description
Running pytest from a git worktree fails with `ModuleNotFoundError` because the root `__init__.py` causes pytest to derive the module name from the worktree directory name, which doesn't correspond to any installed Python package.

Pytest's default prepend import mode walks up from _conftest.py_ looking for the highest directory containing __init__.py. It finds the project root (which has __init__.py), then tries to import conftest.py as `.conftest`. Since the worktree directory name (e.g. my_feature_branch) is not a real Python module, the import fails.

## Steps to Reproduce

1. Create a git worktree: git worktree add ../my_feature_branch some-branch
2. cd ../my_feature_branch
3. Run pytest --collect-only

## Expected Behavior

pytest can be run in and out git worktrees

## Actual Behavior

pytest does not work in git worktrees

## Error Messages/Logs

```text
ImportError while loading conftest '.../my_feature_branch/conftest.py'.
ModuleNotFoundError: No module named 'my_feature_branch'
```

## Environment

- Kubeflow SDK Version: 2.16.0
- Python Version: 3.12.12

## Additional Context

The root cause is the combination of:

* Root __init__.py existing in the project root
* pyproject.toml mapping "kfp_components" = "."
* Pytest's default prepend import mode resolving module names from directory structure

This works on the main checkout but breaks in any worktree (and probably clone with a non-standard directory name).

## Possible Solution

Remove root directory `__init__.py`. The kfp_components package is already properly defined via the [tool.setuptools.package-dir] mapping in pyproject.toml, so import kfp_components works without a root __init__.py. The file currently just contains a docstring and serves no functional purpose beyond triggering this pytest bug in worktrees.

## Willing to Contribute

- [x] Yes, I can submit a fix
- [x] Yes, I can help with testing
- [x] Yes, I can help with documentation
- [ ] No, requesting community help

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Impacted by this bug? Give it a 👍.

Start with the root __init__.py and the package mapping in pyproject.toml, then review the root conftest.py import path described in the issue. Reproduce the failure with pytest --collect-only in a git worktree and verify that collection succeeds there and in the main checkout without the ModuleNotFoundError.

Written by the indexing model from the issue text.