Service worker processes should be identified more easily

Example profile: https://share.firefox.dev/3P0Wh2t

The track `office.com (1/2)` is a service worker process. We can see this especially with `filteredThread.processName` in the console. But because we show the `eTLD+1` information when we have it, we're now missing this information.

I suggested to add it to the tooltip, but Florian thinks it's not visible enough.
Florian suggested to use an icon for this instead of adding more text. I'm not especially convinced but I can be.

Thoughts?

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-561)