Investigate and remove unused fields from widget.json and cached_widget.json

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Close this issue

Context

We recently noticed that the commits_without_merge_commits and default_merge_commit_message fields are not used by the frontend anymore, so we soft-deprecated them in !182725 (merged).

These 2 endpoints (widget.json and cached_widget.json) are called often, and should be limited to only the fields that are in use.

Goal

1. frontend Review all fields from these endpoints and determine if any are no longer needed
2. backend Soft deprecate any fields identified in step 1