Information Panel: hide phonon widget when starting a search

Summary: BUG: 420512

Test Plan:
Select on hove over a video file
Type Ctrl + F
Type some test + enter

Reviewers: ngraham, Dolphin, elvisangelaccio

Reviewed By: ngraham, Dolphin

Subscribers: kfm-devel

Tags: Dolphin

Differential Revision: https://phabricator.kde.org/D29158