notifications: Remove Android summary notification.

Removes the summary notification from the group in
NotificationManager.kt. This allows the user to tap on the body of the
notification to open the app, which was not possible with the summary
notification (only the chevron would expand the
notification, which would then allow the user to interact with the
individual notifications below it.

Please note that removing the summary notification breaks proper
grouping: multiple private messages from the same user will correctly
be grouped together, but stream notifications appear in a separate
notification. This was tested manually.

Fixes part of zulip#5242.

Author: rachelhyman

android/app/src/main/java/com/zulipmobile/notifications/NotificationUiManager.kt

@@ -345,31 +345,10 @@ private fun updateNotification(
         setAutoCancel(true)
     }.build()
 
-    val summaryNotification = NotificationCompat.Builder(context, CHANNEL_ID).apply {
-        setGroup(groupKey)
-        setGroupSummary(true)
-
-        color = context.getColor(R.color.brandColor)
-        setSmallIcon(if (BuildConfig.DEBUG) R.mipmap.ic_launcher else R.drawable.zulip_notification)
-
-        // For the summary we use an "inbox-style" notification, as recommended here:
-        //   https://developer.android.com/training/notify-user/group#set_a_group_summary
-        setStyle(NotificationCompat.InboxStyle()
-            // TODO(#5115): Use the org's friendly name instead of its URL.
-            .setSummaryText(fcmMessage.identity.realmUri.toString())
-            // TODO: Use addLine and setBigContentTitle to add some summary info when collapsed?
-            //   (See example in the linked doc.)
-        )
-
-        // TODO Does this do something useful?  There isn't a way to open these summary notifs.
-        setAutoCancel(true)
-    }.build()
-
     NotificationManagerCompat.from(context).apply {
         // This posts the notifications.  If there is an existing notification
         // with the same tag and ID as one of these calls to `notify`, this will
         // replace it with the updated notification we've just constructed.
-        notify(groupKey, NOTIFICATION_ID, summaryNotification)
         notify(conversationKey, NOTIFICATION_ID, notification)
     }
 }