patch 9.1.1269: completion: compl_shown_match is updated when starting keyword completion

patch 9.1.1269: completion: compl_shown_match is updated when starting keyword completion

Problem:  compl_shown_match is updated when starting keyword completion
          and does not include fuzzy matching.
Solution: Do not update compl_shown_match when starting keyword
          completion, since it is the one already selected by the
          keyword completion direction. (glepnir)

closes: #17033

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>