Ensure user authentication data being flushed when swapping DAM domains

Problem/Motivation

Currently once Acquia DAM has been connected and users have been authenticated, their tokens are saved in users_data table. If a site admin clicks on Disconnect DAM and afterwards changes the DAM domain to a different one, the user data for acquia_dam is not cleared and users are still able to connect to old DAM domain.

Steps to reproduce

1. Once DAM is connected and users have been using DAM in content creation, admin clicks on Disconnect Site button.
2. After disconnecting the site from DAM, change the DAM domain to a different valid URL and submit the form.
3. Expected result: Users already authenticated to use DAM assets should be prompted to authenticate to new DAM.
4. Actual result: Users previously authenticated to use old DAM are still able to use Old DAM and are not prompted to re-authenticate to new DAM. Also any new users authenticating will be using new DAM.

Proposed resolution

Clear the users data on disconnecting DAM.

Remaining tasks

Tests

User interface changes

API changes

Data model changes