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:

When I was doing testing and review in #34679 (review), I found that the new Marketing option checkbox does not show up when we use a build zip.

It seems like that is because the multichannel-marketing flag is set to false in core.json file.

In this PR, we set the value to true. With that, when we build a zip file and upload it to a site, the checkbox would then show up.

How to test the changes in this Pull Request:

1. Run pnpm build.
2. Run pnpm build:zip --filter=woocommerce to build a WooCommerce zip file.
3. In your test site, install or update WooCommerce using the zip file above.
4. Go to WooCommerce Settings > Advanced > Features page. You should see the new Marketing option checkbox, which should be disabled by default.
5. Open another tab and go to the Marketing page: /wp-admin/admin.php?page=wc-admin&path=%2Fmarketing. You should see the normal marketing page.
6. Check the new Marketing option checkbox and save, and then reload the Marketing page. You should see the new beta marketing page.

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 for each project being changed, ie pnpm changelog add --filter=<project>?

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.