Store Mailchimp data in collection

Rebased patch on to the latest 2.x-dev and posted it as a MR. Setting to Needs Review so we get some test feedback.

I did an iteration on the patch. Made some small changes:

• Update documentation to replace mentions of cached lists with stored lists.
• Remove some variable assignments which are no longer needed.
• Align code with latest changes in 2.x-dev branch.

I pushed a temporary second MR that includes the automated test fixed from 📌 2.x branch tests failing Needs review so we can see if we need to update any test coverage.

pfrenssen → closed merge request !64

Used the current MR state with current dev branch on a D10.1.7 and confirm it works.

This looks good, I think. Is it correct to say this will not cause any hiccups on an existing installation that currently uses the cache, the code will simply see the collection is empty and fill it?

@xenophyle I think that's how it worked when I tried this out the first time yes, I didn't have to change anything to switch to using the collection.

This "broke" creating interest groups in https://www.drupal.org/project/webform_mailchimp → , see 🐛 Creating interest groups through Drupal doesn't update the persistent storage Active .

The refresh button is also quite hidden for this, if you for example use webform_mailchimp then you likely aren't setting up any signup forms, would be nice if there were a refresh button on the main settings page.

Automatically closed - issue fixed for 2 weeks with no activity.