Make rabbit_fifo_dlx_sup more resilient

Previously, it used the default intensity:
"intensity defaults to 1 and period defaults to 5."

However, it's a bit low given there can be dozens or hundreds of DLX
workers: If only 2 fail within 5 seconds, the whole supervisor
terminates.

Therefore, this commit bumps this value from 1 to 10.

Even with a value of 10, there shouldn't be any infnite loop of the
supervisor terminating and restarting childs because the
rabbit_fifo_dlx_worker is terminated and started very quickly
given that the (the slow) consumer registration happens in
rabbit_fifo_dlx_worker:handle_continue/2.

Author: ansd

deps/rabbit/src/rabbit_fifo_dlx_sup.erl

@@ -24,7 +24,7 @@ start_link() ->
 
 init([]) ->
     SupFlags = #{strategy => simple_one_for_one,
-                 intensity => 1,
+                 intensity => 10,
                  period => 5},
     Worker = rabbit_fifo_dlx_worker,
     ChildSpec = #{id => Worker,