Remove obsolete telemetry storage and testing files for GNMI OpenConfig

- Deleted StorageInterface.py, StorageNetworkInstance.py, and Tools.py as they are no longer needed.
- Removed associated test files and utility scripts that were dependent on the deleted storage classes.
- Cleaned up the tools directory by removing unused request composers and result config adapters.
- Ensured that all related imports and references in the test suite are also removed to maintain code integrity.