Annotate profiles when slowdowns with known causes are detected

Recently we had someone asking about a profile that seemed to be spending a lot of time capturing the stack. It turns out, that this only happens if a non-standard pref is set -or- Devtools is open.

I wonder if we could annotate either whole profiles, or even just frames, indicating "Hey, if you see this and are worried about this, have you tried... " (in this case, closing devtools and trying again).

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-881)