Add "Remove Firefox Profiler Menu Button" to profiler.firefox.com landing page

See issue #3184 for the reason (users may not know how to remove the profiler button).

Since https://profiler.firefox.com is the main page used to initially add the toolbar button, and it knows not to show the "Enable..." button anymore after it has been enabled, I would suggest that the same button area be reused to allow easy removal of the profiler toolbar button.
This would make the page a bit more consistent before and after.
And I think it would be one of the most obvious location where users would look at to remove the toolbar button when no longer needed.

Enable button:

Suggested "Remove" button:

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-371)