R1:d3280c406d59

When repositories hit pull errors, stop updating them as frequently

Summary:
Ref T11665. Currently, when a repository hits an error, we retry it after 15s. This is correct if the error was temporary/transient/config-related (e.g., bad network or administrator setting up credentials) but not so great if the error is long-lasting (completely bad authentication, invalid URI, etc), as it can pile up to a meaningful amount of unnecessary load over time.

Instead, record how many times in a row we've hit an…