Revert "Pass fully-qualified arguments and return values to moc"

This could break old-style connects. Let's keep it as it was until KF6
as discussed in the channel. Thanks frinring for pointing it out.

This reverts commit f631aec33f.

src/plasma/datacontainer.h

@@ -244,7 +244,7 @@ Q_SIGNALS:
      * @param source  the datacontainer the update was requested for.  Useful
      *                for classes that update the data for several containers.
      **/
-    void updateRequested(Plasma::DataContainer *source);
+    void updateRequested(DataContainer *source);
 
 protected:
     /**

src/plasma/dataengine.h

@@ -93,7 +93,7 @@ public:
      *         is parented to the DataEngine, but should be deleted by the
      *         caller when finished with it
      */
-    Q_INVOKABLE virtual Plasma::Service *serviceForSource(const QString &source);
+    Q_INVOKABLE virtual Service *serviceForSource(const QString &source);
 
     /**
      * @return description of the plugin that implements this DataEngine
@@ -177,7 +177,7 @@ public:
      * @param source the name of the source.
      * @return pointer to a DataContainer, or zero on failure
      **/
-    Q_INVOKABLE Plasma::DataContainer *containerForSource(const QString &source);
+    Q_INVOKABLE DataContainer *containerForSource(const QString &source);
 
     /**
      * @return The model associated to a source if any. The ownership of the model stays with the DataContainer.

src/plasma/service.h

@@ -135,7 +135,7 @@ public:
      * @return a started ServiceJob; the consumer may connect to relevant
      *         signals before returning to the event loop
      */
-    Q_INVOKABLE Plasma::ServiceJob *startOperationCall(const QVariantMap &description, QObject *parent = nullptr);
+    Q_INVOKABLE ServiceJob *startOperationCall(const QVariantMap &description, QObject *parent = nullptr);
 
     /**
      * Query to find if an operation is enabled or not.