patch 9.1.1563: completion: ruler may disappear

Problem:  The ruler disappears after typing the second character during
          insert mode completion, even when completion messages are
          suppressed ('shortmess' includes "c"). This makes the UI
          appear inconsistent.
Solution: Ensure the ruler is restored during screen redraw when popup
          completion is active (Girish Palya).

Notes:
No new tests were added, as existing screen dump tests were updated to
reflect the corrected behavior.

closes: #17770

Signed-off-by: Girish Palya <girishji@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: girishji