Improvement Implemented: Remove Obsolete Parameter Migration Function

[tomwolfe]

Change Made:

• File: openpilot/selfdrive/locationd/paramsd.py
• Removed: The function migrate_cached_vehicle_params_if_needed() which was marked for removal after version 0.9.9
• Removed: The call to this function in the main() function

Safety/Stability Impact:

• Code cleanliness: Removes dead code that was no longer needed since version 0.9.9
• Reduced complexity: Eliminates unnecessary parameter migration logic that could potentially cause issues
• Maintainability: Reduces codebase size and removes technical debt

Verification:

• The function was only used for migrating old parameter format to new format (LiveParameters → LiveParametersV2)
• Since this migration was for version 0.9.9 and current versions are much newer, this code is obsolete
• The main parameter retrieval logic (retrieve_initial_vehicle_params) continues to work with the current LiveParametersV2 format
• No functional change to the parameter learning system - it will continue to work exactly the same way

PR Details:

• Title: "Cleanup: Remove obsolete parameter migration function"
• Changes: ≤ 10 lines removed (the function definition and its call)
• Impact: Code cleanup with no functional changes to active logic
• Safety: Improves code safety by removing unused, potentially problematic code

This change aligns with the project's goals of maintaining a clean, safe codebase by removing obsolete functionality that's no longer needed in current and future releases.