progress: remove progress.estimate config It was introduced by 98e4d39 ("progress: add speed format" 2011-5-9) and was intended to hide ETA information for the first few seconds. Later 5d261fd ("progress: add a changedelay to prevent parallel topics from flapping (issue2698)" 2011-6-23) introduced `changedelay` config which hides the entire progress bar for the first few seconds. So `progress.estimate` seems somehow duplicated feature-wise. Since it's experimental and duplicated, let's just remove it. This makes the next patch simpler - it no longer needs to make sure `starttimes` is the real start time. Differential Revision: https://phab.mercurial-scm.org/D828