Timeline: Don't mess with room header padding

Recalculation of padding depending on whether the scroll bar is there
can easily break the already fragile layout logic, bringing minimal
benefits in return (it was made to avoid the text ending up under
transient scrollbars that are overlapping with the client area - but
transient scrollbars disappear after scrolling anyway).

Hopefully fixes #916.

client/qml/Timeline.qml

@@ -153,8 +153,6 @@ Page {
                     id: topicText
                     padding: 2
                     leftPadding: headerText.innerLeftPadding
-                    rightPadding: topicField.ScrollBar.vertical.visible
-                                  ? topicField.ScrollBar.vertical.width : padding
 
                     text: room ? room.prettyPrint(room.topic) : ""
                     placeholderText: qsTr("(no topic)")