Follow-up pass for renaming Usage Ping/Data to Service Ping/Data

After closing the blocking issues, we need to do another pass to remove any leftover variables, references, and symbols that might reference Usage Ping/Data. For example:

• Documentation links like: help_page_path('development/usage_ping/index.md')
• Ruby variables for frontend (example)
• Some filenames. Easy to rename but it might produce conflicts as we're actively working over these files.