docs: remove out-of-scope test documentation from CONTRIBUTING.md

Signed-off-by: Giannis <giannisgeorgiadiis@gmail.com>

Author: Giannis-dot

CONTRIBUTING.md

@@ -168,23 +168,3 @@ Thank you for contributing to the Hiero Python SDK! 🎉
     - Join the main [Linux Foundation Decentralized Trust (LFDT) Discord Server](https://discord.gg/hyperledger).
     - Go directly to the [#hiero-python-sdk channel](https://discord.com/channels/905194001349627914/1336494517544681563)
 
----
-
-## Running tests locally
-
-During development you may want to run a single test file in isolation to avoid importing the project's package-level `__init__` (which imports generated protobuf modules). To run a single test file without loading project-wide fixtures, use the project's virtualenv Python and run pytest on the path:
-
-PowerShell example:
-```powershell
-# activate virtualenv (if not already active)
-C:/Users/Giannis/OneDrive/Programming/hiero-sdk-python/.venv/Scripts/Activate.ps1
-
-# install test deps if needed
-python -m pip install -U pip
-python -m pip install pytest
-
-# run a single test file
-python -m pytest -q tests/test_subscription_handle.py
-```
-
-If you want to run a subset of tests, use `-k` with a keyword expression or provide a directory/file path. This helps avoid heavy `conftest.py` imports during quick iteration.