Notify teams about comments on closed issues

[chadwhitacre]

From @lforst @bruno-garcia in Slack:

We need to find a solution for closed issues that receive comments. Right now they completely fly past us, unless someone who currently still works at sentry is subscribed.
One example: Unless Kamil (who doesn’t work at Sentry anymore) had pinged me on this issue, we would have never noticed it received a comment. This is not an edge case. getsentry/sentry-cli#1228

having the bot ping us on closed issues is ok i’d say. And we can lock issues if we thing things are out of topic/done.
ping us I mean on slack as we get for triaging

I’d be in favor of adding a waiting for product owner label I think. It would be consistent with the process. If we do not want more interactions on a particular issue, we can always lock it.