Merged PR 5403: Removes test accounts

# Description

This PR directly removes test accounts, and not just flag them, from:
* `int_core__unified_user`, which means is also propagated to `int_core__user_host`.

It does so by creating a new, extremely simple model named: `int_core__user_test_account`

Then, `int_core__user_host` is inner joined with a small explanation comment on:
* `int_core__accommodation`
* `int_core__unique_accommodation_to_user`
* `int_core__bookings`
* `int_core__verification_requests`
* `int_core__payments`

Effectively removing test accounts.

Lastly, any existence and usage of the column `is_test_account` has been removed -> mostly on New Dash-related models.

# Checklist

**As discussed in the daily, I'll be playing around in prod with this PR**

- [ ] The edited models and dependants run properly with production data.
- [ ] The edited models are sufficiently documented.
- [ ] The edited models contain PK tests, and I've ran and passed them.
- [ ] I have checked for DRY opportunities with other models and docs.
- [ ] I've picked the right materialization for the affected models.

# Other

- [ ] Check if a full-refresh is required after this PR is merged.

Related work items: #27319

models/intermediate/cross/int_new_dash_deal_onboarding.sql

@@ -38,7 +38,6 @@ with
             -- Filters to replicate New Dash Overview
             icuh.is_user_in_new_dash = true
             and icuh.is_missing_id_deal = false
-            and icuh.is_test_account = false
             -- Filter to only select new business (i.e., not migrated from Old Dash)
             and icuh.has_user_moved_from_old_dash = false
         group by 1, 2, 3, 4, 5, 6, 7, 8
@@ -88,7 +87,6 @@ with
             -- Filters to replicate New Dash Overview
             icuh.is_user_in_new_dash = true
             and icuh.is_missing_id_deal = false
-            and icuh.is_test_account = false
             -- Filter to only select new business (i.e., not migrated from Old Dash)
             and icuh.has_user_moved_from_old_dash = false
         group by 1