Fix memory leak in Worker when map is removed (#3733)

[pasieronen]

Fixes #3733

• Confirm your changes do not include backports from Mapbox projects (unless with compliant license) - if you are not sure about this, please ask!
• Briefly describe the changes in this PR.
• Link to related issues.
• Include before/after visuals or gifs if this PR includes visual changes.
• Write tests for all new functionality.
• Document any changes to public APIs.
• Post benchmark scores.
• Add an entry to CHANGELOG.md under the ## main section.

[HarelM]

Thanks for taking the time to open this PR!
Jest tests are using a message bus implementation that simply doesn't use a worker but uses the same "thread".
Also there's a template for the PR which helps making sure everything is added like changelog (which is missing, mapbox packporting) etc.
There are some tests that check all kind of dispatched messages etc I would recommend looking at those.
Bottom line, this needs tests.

[HarelM]

Besides the above nit picking, this looks good, thanks!
Once changelog conflicts are resolved, I'll merge this.