autotests: remove code duplication by moving try+catch+qWarning+qFatal to FakeAkonadiServer
Summary: Less code to write in new unittests is always a good thing
Test Plan:
ctest, all passed except akonadi-sqlite-referencetest, which is unrelated
and on death row anyway.
Reviewers: dvratil
Reviewed By: dvratil
Subscribers: kde-pim
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D20355