Removed unnecessary margins in chat session and participant list items

resources/chat_session.ui

@@ -108,16 +108,7 @@
    <property name="spacing">
     <number>3</number>
    </property>
-   <property name="leftMargin">
-    <number>2</number>
-   </property>
-   <property name="topMargin">
-    <number>0</number>
-   </property>
-   <property name="rightMargin">
-    <number>1</number>
-   </property>
-   <property name="bottomMargin">
+   <property name="margin">
     <number>0</number>
    </property>
    <item>