KCM: Remove extra margins

kcm/kcm.cpp

@@ -506,8 +506,7 @@ void KCMNetworkmanagement::loadConnectionSettings(const NetworkManager::Connecti
                 kcmChanged(valid);
             }
         });
-        auto layout = new QVBoxLayout(m_ui->connectionConfiguration);
-        layout->addWidget(m_tabWidget);
+        m_ui->horizontalLayout->addWidget(m_tabWidget);
     }
 
     kcmChanged(false);
@@ -593,7 +592,6 @@ void KCMNetworkmanagement::resetSelection()
     QObject *rootItem = m_ui->connectionView->rootObject();
     QMetaObject::invokeMethod(rootItem, "deselectConnections");
     if (m_tabWidget) {
-        delete m_ui->connectionConfiguration->layout();
         delete m_tabWidget;
         m_tabWidget = nullptr;
     }

kcm/kcm.ui

@@ -23,6 +23,9 @@
    </size>
   </property>
   <layout class="QHBoxLayout" name="horizontalLayout">
+   <property name="margin">
+    <number>0</number>
+   </property>
    <item>
     <widget class="QQuickWidget" name="connectionView">
      <property name="resizeMode">
@@ -30,9 +33,6 @@
      </property>
     </widget>
    </item>
-   <item>
-    <widget class="QWidget" name="connectionConfiguration" native="true"/>
-   </item>
   </layout>
  </widget>
  <customwidgets>

libs/editor/connectioneditortabwidget.ui

@@ -11,6 +11,9 @@
    </rect>
   </property>
   <layout class="QGridLayout" name="gridLayout">
+   <property name="margin">
+    <number>0</number>
+   </property>
    <item row="0" column="0">
     <widget class="QLabel" name="label">
      <property name="text">