Remove primary CTA button from cannotDeleteModal

What does this MR do and why?

Since switching to the tabbed self-hosted models experience, the aiFeatureSettingsPath is redundant as it leads to the old page. There is currently no alternative as we don't support tabbed routes yet. Support will be added in 17.6. Until then, to ensure we don't have a broken user experience at the end of 17.5, we will remove the CTA button linking to that route when displaying the cannotDeleteModal. There are no designs as this is a patch fix which has been made in consult with the Custom Models designer @timnoah.

MR acceptance checklist

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Screenshots or screen recordings

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Before	After

How to set up and validate locally

Prequisites

You will need an active GitLab ultimate license.

1. Start GDK instance in self-managed mode:

GITLAB_SIMULATE_SAAS=0 && gdk start

2. In the rails console, enable Code Suggestions and the custom models experiment:

Feature.enable(:ai_custom_model)
Feature.enable(:custom_models_vue_app)
Feature.enable(:custom_models_feature_settings_vue_app)
ApplicationSetting.first.update(duo_features_enabled: true)

Test it!

1. Log in as an admin
2. Visit the page Admin Area > Self-hosted models
   
3. In the Self-hosted models tab, create a mistral model.
4. Navigate to the Ai-powered features tab and link any feature to the model created from the previous step
5. Navigate back to the Self-hosted models tab and click "delete" on the model (hidden in the 3 dot kebab). This will open the cannotDeleteModal as seen in the screenshots.
6. To validate that this change does not impact the canDelete modal, create another self-hosted model without linking it to a feature. Click "delete" on the model — it should bring up the canDelete modal with CTA: