Clean up integrations.type column

Part of &6177 (closed)

Addresses:

• #330443 (closed)
• #333509 (closed)

What does this MR do and why?

Now that the integrations.type column is no longer in use, the following schema elements can be removed:

• the trigger and function keeping type in sync with type_new
• the indices on the type column
• the type column itself

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #333508 (closed)