mod_stream_mgmt: Clean up on timed out resumption

During resumption, make sure the old process and the corresponding
session entry are disposed also in the case where the call that queries
the old process times out.

src/mod_stream_mgmt.erl

@@ -664,6 +664,8 @@ inherit_session_state(#{user := U, server := S,
 			  exit:{normal, _} ->
 			    {error, <<"Previous session PID has exited">>};
 			  exit:{timeout, _} ->
+			    ejabberd_sm:close_session(OldSID, U, S, R),
+			    ejabberd_c2s:stop(OldPID),
 			    {error, <<"Session state copying timed out">>}
 		    end
 	    end;