Remove unused files

src/autotests/CMakeLists.txt

-add_executable( contactfieldstest contactfieldstest.cpp ../contactfields.cpp )
-add_test( NAME contactfieldstest COMMAND contactfieldstest )
-ecm_mark_as_test(kaddrebook-contactfieldstest)
-target_link_libraries(contactfieldstest  KF5::Contacts Qt::Test Qt::Gui KF5::I18n)

src/tests/CMakeLists.txt

-set(newdesigntest_SRCS
-    main.cpp
-    )
-
-add_executable(newdesigntest ${newdesigntest_SRCS})
-
-target_link_libraries(newdesigntest
-    Qt::Widgets
-    KF5::Contacts
-    KF5::I18n
-    KF5::Completion
-    KF5::WidgetsAddons
-    )
-

src/tests/main.cpp

-/*
-    SPDX-FileCopyrightText: 2016-2021 Laurent Montel <montel@kde.org>
-
-    SPDX-License-Identifier: LGPL-2.0-or-later
-*/
-
-#include <QApplication>
-int main(int argc, char *argv[])
-{
-    QApplication app(argc, argv);
-    return app.exec();
-}