Fix #6362, avoid overriding def peer repeatedly

def peer is a method that gets repeated a lot in modules, so we
should have it in the tcp mixin. This commit also clears a few
modules that use the HttpClient mixin with def peer.

lib/msf/core/exploit/java/rmi/client.rb

@@ -51,12 +51,6 @@ module Msf
               datastore['RPORT']
             end
 
-            # Returns the RMI server peer
-            #
-            # @return [String]
-            def peer
-              "#{rhost}:#{rport}"
-            end
 
             # Sends a RMI header stream
             #