[shell] Show kactivies warning only on error
load() is called a few times and different states. After the change I
also get the warning on a regular load.
This patch returns early whilst we're in the loading state, but still
prints the warning should kactivitymanagerd fail.
Reviewers: Plasma, mart
Reviewed By: Plasma, mart
Differential Revision: https://phabricator.kde.org/D18922