GHA cache: report failures to Sentry

[edigaryev]

And also move towards structured logging a bit more by parametrizing the failure attributes.

Looks like this (note the url, which github.com/getsentry/sentry-go/http package provides:

And this:

[fkorotkov]

I think we need to make sure we pass SENTRY_DNS to the agent and make sure the agent is not leaking it to script instructions.

[edigaryev]

Let's merge this as is for now, I'll follow-up with either a (1) SENTRY_DSN passthrough or (2) a way to collect these logs in Persistent Worker and tag them with a task ID and other tags.