Sunset the Web Worker Offloading plugin

Feature Description

The Web Worker Offloading plugin was an experiment to see if we could leverage Partytown to improve INP. However, I have yet to see any reports that it improves anything. By contrast, I've only seen poor reviews and problems in the support forum. I suggest we remove Web Worker Offloading from being listed among the Performance features to install.

There are currently 20K+ active installations of the plugin right now. To gather feedback from users to find out if they are finding it improves INP in any way, we can perhaps show a banner on the top of the Performance screen advising users that we're considering turning down the experiment. If they find it is useful, we could ask them to submit feedback to the support forum.

We can add a notification dot next to the Performance menu item if they have the Performance Lab plugin active. If they don't have the Performance Lab plugin, we'll have to figure out an alternative way to notify users of our plans to sunset. Maybe we'll have to show the banner at above the plugin list table.

Start by tracing the Performance screen, Performance menu item, and plugin list table mentioned in the issue, then review how Web Worker Offloading is currently listed. Clarify the notification and feedback approach with maintainers; done means an agreed sunset communication path and removal from the Performance features list.