Add Planner to user statistics

What does this MR do and why?

Related to #482733 (closed) (task: Add Planner to user statistics (#504309 - closed))

Follow-up to Add new static role Planner (!169256 - merged) that adds with_highest_role_planner field to the users_statistics table to display the role in the User statistics admin page.

Database changes

Migrate Up

bin/rails db:migrate:up:main VERSION=20241029130136
main: == [advisory_lock_connection] object_id: 129020, pg_backend_pid: 83843
main: == 20241029130136 AddWithHighestRolePlannerToUsersStatistics: migrating =======
main: -- add_column(:users_statistics, :with_highest_role_planner, :integer, {:default=>0, :null=>false})
main:    -> 0.0161s
main: == 20241029130136 AddWithHighestRolePlannerToUsersStatistics: migrated (0.0206s)

main: == [advisory_lock_connection] object_id: 129020, pg_backend_pid: 83843

Migrate Down

❯ bin/rails db:migrate:down:main VERSION=20241029130136
main: == [advisory_lock_connection] object_id: 129020, pg_backend_pid: 83288
main: == 20241029130136 AddWithHighestRolePlannerToUsersStatistics: reverting =======
main: -- remove_column(:users_statistics, :with_highest_role_planner, :integer, {:default=>0, :null=>false})
main:    -> 0.0052s
main: == 20241029130136 AddWithHighestRolePlannerToUsersStatistics: reverted (0.0116s)

main: == [advisory_lock_connection] object_id: 129020, pg_backend_pid: 83288

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. In Rails console generate some user statistics data

FactoryBot.create(:users_statistics)

2. With an admin user visit the Users statistics page (eg. http://gdk-test:3000/admin/dashboard/stats)
3. Verify the column Users with highest role Planner exists