User gets in a confusing state when they click the edit link on a monitor they don't own

[benvenker]

https://sourcegraph.slack.com/archives/C03CSAER9LK/p1659016146331619?thread_ts=1658915266.026149&cid=C03CSAER9LK

Hey, I clicked the “edit your code monitor” link in this message, knowing well that I’m not Tom and won’t be able to edit it — but did expect some sorta error to show up instead.

[sourcegraph-bot-2]

Heads up @benvenker @lguychard - the "team/search-product" label was applied to this issue.