Mark marketing task as complete when an extension is installed

[octaedro]

All Submissions:

• Have you followed the WooCommerce Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Closes #32149.

How to test the changes in this Pull Request:

1. In a brand new store, go through the OBW, and in step 4 (Business Details), go to Free features and install the MailPoet extension.
2. Finish the OBW.
3. Go to the Home screen and verify that the marketing task is marked as completed.
4. Delete the MailPoet extension.
5. Verify that the marketing task is not marked as completed now.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?
• Have you created a changelog file by running pnpm nx affected --target=changelog?

FOR PR REVIEWER ONLY:

• I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.

[joelclimbsthings]

Just curious, this condition seems a little redundant with the first one, since $remaining is just the inverse of $installed, but perhaps it's needed to capture the condition that there are no plugins?

[octaedro]

Nice catch! I removed the redundant condition in commit 48a3724

[joelclimbsthings]

Thanks @octaedro , tests well and looks good. Left a quick question, but not a blocker by any means. 🚢

[octaedro]

Thank you @joelclimbsthings for the review, I addressed the change you mentioned.
Could you take another look at this PR?

[joelclimbsthings]

Right on @octaedro , looks great! 🚢

[github-actions]

Hi @octaedro, thanks for merging this pull request. Please take a look at these follow-up tasks you may need to perform:

• Add the release: add testing instructions label