releases: proceed to final tag as fast as possible
Created by: bobheadxi
Closes https://github.com/sourcegraph/sourcegraph/issues/14911 by updating the instructions to indicate releases should proceed to a final tag as fast as possible.
Also removes steps about reviewing milestone tasks since that doesn't really seem to happen, and add a step to post a release status update whenever a candidate is cut (which will include links to blocking issues and milestone issues)