Extension info isn't really stripped when requested from profiles

After capturing a profile and clicking publish, then unchecking the "include extension information" checkbox, I downloaded the profile json and poked around in it. Even though the `meta.extensions` section is removed. by looking through the data in `threads[].stringArray`, you can effectively get a list of extension names and IDs.

For example, I ran the json through a pretty printer, then `grep \"Extension pretty.json | sort -u` prints out exactly the extensions I am running.

I guess that info happens to incidentally be a part of other collected data.

There are also some domains listed related to tabs I had open that could possibly identify sites. In my case, I had a Gmail tab open and `0.client-channel.google.com`, `contacts.google.com`, `mail.google.com` appear.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-296)