insights: infer insight permissions from dashboards when updating
Created by: CristinaBirkel
Regarding https://github.com/sourcegraph/sourcegraph/issues/27837
Doesn't close this issue because the larger issue is that series are being re-processed, but it does fix the errored response.
Description
I did it this way just because it seems very straight-forward. I'm not sure if we need GetMapped
anymore at all, but it's very close to a release and I think this is a minimal change we can make for the short term.
Testing Steps
I tested this by updating an insight that did not have any grants attached to it that my user could see, (but the insight is on a global dashboard,) and verified that I get back a response.