perf: autocomplete owner/configuration on Route admin change page

[chrisdoehring]

Summary

Follow-up to #424. That PR fixed the dominant cause of the Route admin change-page timeout by adding autocomplete_fields to the inline integration FKs (an N+1 storm that scaled with the Integration table).

The main change form still renders the owner and configuration ForeignKeys as plain <select> dropdowns that eagerly load every Organization / RouteConfiguration row. These are single selects rendered once each — not the N+1 inline storm — but they still grow with those tables and add unnecessary weight to the page. This switches them to autocomplete for consistency and to keep the change page light as those tables grow.

Changes

• RouteAdmin.autocomplete_fields = ("owner", "configuration") (OrganizationAdmin already has search_fields).
• Added search_fields = ("id", "name") to RouteConfigAdmin so configuration qualifies for autocomplete.
• Test asserting both fields render Django's AutocompleteSelect widget (unwrapping RelatedFieldWidgetWrapper).

Verification

• integrations/tests/test_admin.py — 2 passed (the existing fix: stop Route admin change page from timing out #424 scaling test plus the new widget test).
• manage.py check passes (validates the autocomplete_fields / search_fields wiring).

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR is a follow-up performance improvement to the Django admin Route change page. It reduces page weight by switching the owner and configuration ForeignKey widgets from eager-loading <select> dropdowns to Django admin’s AJAX-backed autocomplete widgets, keeping the change form responsive as Organization and RouteConfiguration tables grow.

Changes:

• Enabled autocomplete_fields for RouteAdmin.owner and RouteAdmin.configuration.
• Added search_fields to RouteConfigAdmin to satisfy Django’s autocomplete requirements for the configuration FK.
• Added an admin test asserting both fields render as AutocompleteSelect widgets (handling RelatedFieldWidgetWrapper).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
cdip_admin/integrations/admin.py	Switches Route admin FK widgets to autocomplete and adds search_fields for RouteConfiguration to support it.
cdip_admin/integrations/tests/test_admin.py	Adds coverage ensuring the Route change form uses autocomplete widgets for owner and configuration.

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[chrisdoehring]

@victorlujanearthranger this is a follow-up PR, not urgent but useful when looking at Routes in the Django admin.