install plugins in pim5 it's more logical

src/kmailtransport/plugins/smtp/CMakeLists.txt

 if (BUILD_TESTING)
     add_subdirectory(autotests)
 endif()
-kcoreaddons_add_plugin(mailtransport_smtpplugin INSTALL_NAMESPACE "kf${QT_MAJOR_VERSION}/mailtransport")
+kcoreaddons_add_plugin(mailtransport_smtpplugin INSTALL_NAMESPACE "pim${QT_MAJOR_VERSION}/mailtransport")
 
 target_sources(mailtransport_smtpplugin PRIVATE
     smtpmailtransportplugin.cpp

src/kmailtransport/plugins/transportpluginmanager.cpp

@@ -55,7 +55,7 @@ void TransportPluginManagerPrivate::initializePlugins()
     if (!mPluginList.isEmpty()) {
         return;
     }
-    const QVector<KPluginMetaData> plugins = KPluginMetaData::findPlugins(QStringLiteral("kf" QT_STRINGIFY(QT_VERSION_MAJOR) "/mailtransport"));
+    const QVector<KPluginMetaData> plugins = KPluginMetaData::findPlugins(QStringLiteral("pim" QT_STRINGIFY(QT_VERSION_MAJOR) "/mailtransport"));
 
     QVectorIterator<KPluginMetaData> i(plugins);
     i.toBack();

src/kmailtransportakonadi/plugins/CMakeLists.txt

-kcoreaddons_add_plugin(mailtransport_akonadiplugin INSTALL_NAMESPACE "kf${QT_MAJOR_VERSION}/mailtransport")
+kcoreaddons_add_plugin(mailtransport_akonadiplugin INSTALL_NAMESPACE "pim${QT_MAJOR_VERSION}/mailtransport")
 target_sources(mailtransport_akonadiplugin PRIVATE
     akonadimailtransportplugin.cpp
     resourcesendjob.cpp