Change the query loading progress bar

Change the magnifying glass icon to spinning progress bar when query runs longer, and remove existing progress bar line

Start by locating the query loading UI and the code that displays the magnifying glass and existing progress-bar line. Run a long-running query to observe the current behavior and identify the relevant entry point. Done means the icon changes to a spinning progress indicator for long queries and the existing progress-bar line is removed.

Written by the indexing model from the issue text.