kwayland-integration: fix compilation with no-deprecated build of kwindowsystem

Summary:
I build kwindowsystem with -DEXCLUDE_DEPRECATED_BEFORE_AND_AT=5.62.0,
and this broke here. Use the exact same condition as the one around
those virtual methods in the base class.

This required upgrading the KF5 requirement from 5.62 to 5.64,
so no backport to Plasma/5.17 unfortunately.

Reviewers: kossebau, jriddell, davidedmundson

Reviewed By: kossebau

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D25488