Integrations involving Azure API Management that utilize a custom domain

# Description

When integrating API Center with an API Management Service that uses a custom domain, a new deployment is created automatically. However, it will use the APIM built-in Gateway hostname .azure-api.net instead of the custom domain. There is currently no way to change this.

# Reproduction steps

Steps to reproduce the behavior:

1. Create a new integration in API Center
- Platforms
- Integrations
- New Integration
- From Azure API Management
Complete the wizard

2. Go to Deployments and locate the deployment that was created. Check the Deployment Runtime, and you'll see .azure-api.net/ as the base URL, which cannot be changed to a custom domain. In the API Center Portal, the built-in hostname will also appear.

# Expected behavior

The intended functionality is for the custom domain set in API Management to be automatically used for deployments created during new integration setups, or at minimum, to provide an option to manually edit the runtime URL afterwards.

# Actual behavior

The current behavior is that the field is greyed out only for Deployments created automatically when a new integration is set up, and it cannot be changed. However, for Deployments created manually, this field remains enabled.