Revert "Add stealthmins (#26263)"

This reverts commit dca0c6694b.

# Conflicts:
#	Content.Server/Administration/Commands/AdminWhoCommand.cs
#	Content.Server/Administration/Managers/AdminManager.cs
#	Content.Server/Chat/Managers/IChatManager.cs

Content.Shared/Administration/AdminFlags.cs

@@ -104,11 +104,6 @@ namespace Content.Shared.Administration
         /// </summary>
         MassBan = 1 << 17,
 
-        /// <summary>
-        /// Allows you to remain hidden from adminwho except to other admins with this flag.
-        /// </summary>
-        Stealth = 1 << 16,
-
         /// <summary>
         ///     Dangerous host permissions like scsi.
         /// </summary>