Remove validation index page

[benjamineskola]

Description of change

Now that all application types use the tasks model and sidebar, we don't ever need to show the old validation index page. Instead, redirect to the first available task, and remove all the leftover views.

Story Link

https://trello.com/c/OTZ31KzH/1769-validation-sidebar-for-all-applications-starts-with-first-task-hide-old-tasklist-view

[benjamineskola]

I've left this in place to account for leftover references to it, but it might be overkill. (I'd make it a redirect, but the action it points at is already a redirect.)

[benbaumann95]

This might be intentional but worth just sense checking (I'm lacking a bit of context):

Think these actions still call the old route helpers.

app/controllers/planning_applications_controller.rb#L118
planning_application_validation_sitemap_path.
This is in the redirect_update_url or boundary geojson validation logic.

_validation_request_show_actions.html.erb:15
planning_application_validation_fee_items_path. This shared partial renders a "Continue" button for closed/active fee validation requests.

ownership_certificate_validation_requests/_show.html.erb:75
edit_planning_application_validation_ownership_certificate_path.
This renders a link saying "If this is incorrect, create another ownership certificate validation request". Viewing any ownership certificate validation request will break.

red_line_boundary_change_validation_requests/_applicant_rejected_response.html.erb:24
planning_application_validation_sitemap_path.
This is the "Continue" button shown when an applicant rejects a red line boundary change.

document/redactions/_form.html.erb:3
planning_application_validation_documents_redactions_path
submitting the redaction form will POST to a URL that doesn't exist (404).