Fix some corner case where a wrong display name would show

Scenario: Scroll to a message in dual side bubble layout that:
- Is an image, i.e. has a time footer overlay
- Was sent by the user
- Was sent in a group chat, i.e. other messages show sender display
  names

This scenario could lead to the non-bubble name view not being cleared
nor hidden correctly.

Change-Id: I033d3070612d219dea9f2181c5029e17460c3ee6

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/item/AbsMessageItem.kt

@@ -134,8 +134,10 @@ abstract class AbsMessageItem<H : AbsMessageItem.Holder> : AbsBaseMessageItem<H>
                 if (attributes.informationData.showInformation) {
                     if (canHideSender) {
                         // In the case of footer time, we can also hide the names without making it look awkward
-                        hiddenViews.add(holder.bubbleMemberNameView)
-                        memberNameView = null
+                        if (memberNameView != null) {
+                            hiddenViews.add(memberNameView)
+                            memberNameView = null
+                        }
                         hiddenViews.add(holder.bubbleTimeView)
                     } else if (!senderInBubble) {
                         // We don't need to reserve space here