Obsolete other popup stuff (#11442)

Content.Server/Popups/PopupExtensions.cs

@@ -12,6 +12,7 @@ namespace Content.Server.Popups
         /// </summary>
         /// <param name="source">The entity on which to popup the message.</param>
         /// <param name="message">The message to show.</param>
+        [Obsolete("Use PopupSystem.PopupEntity instead")]
         public static void PopupMessageOtherClients(this EntityUid source, string message)
         {
             var viewers = Filter.Empty()
@@ -42,6 +43,7 @@ namespace Content.Server.Popups
         /// <param name="range">
         ///     The range in which to search for players, defaulting to one screen.
         /// </param>
+        [Obsolete("Use PopupSystem.PopupEntity instead")]
         public static void PopupMessageEveryone(this EntityUid source, string message, IPlayerManager? playerManager = null, int range = 15)
         {
             source.PopupMessage(message);