Revert "Load the keyboard on-demand"

This reverts commit 5c39795b88d33e53153dedd62eeae2a821ccf09d.

This unfortuntaely introduces the regression on the phone where there's
multiple bugs preset,

• Keyboard can no longer be closed using close button, or removing focus.
• Opening keyboard makes application get no input events, making it look like it is crashed/stuck or hung.

I failed to reproduce this bug on desktop unfortunately.

CCMAIL: Aleix Pol <aleixpol@kde.org>