Log data discrepancies when use_user_group_member_roles flag is enabled

What does this MR do and why?

Previously, track_diff method operates on the assumption that use_user_group_member_roles is disabled and receives the results of executing union_query as its argument. It then executes user_group_member_roles_query to fetch the other set of results, compares them, and logs any discrepancies.

This MR updates track_diff method to log data discrepancies between results of union_query and user_group_member_roles_query when use_user_group_member_roles feature flag is enabled or disabled.

This will allow us to monitor and check logged data discrepancies between using the existing query (union_query) and querying from user_group_member_roles table (user_group_member_roles_query) once we enable use_user_group_member_roles feature flag.

References

This is a requirement for Rollout use_user_group_member_roles (#554706 - closed).

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How to set up and validate locally

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