Fix test flake

Increase waiting for credit being applied as described in commit
aeedad7 since this test case still flakes rarely with:
```
=== === Reason: {assertEqual,[{module,amqp_client_SUITE},
                               {line,3030},
                               {expression,"amqp10_msg : body ( Msg1 )"},
                               {expected,[<<"1">>]},
                               {value,[<<"2">>]}]}
  in function  amqp_client_SUITE:detach_requeues_two_connections/2 (amqp_client_SUITE.erl, line 3030)
  in call from test_server:ts_tc/3 (test_server.erl, line 1793)
  in call from test_server:run_test_case_eval1/6 (test_server.erl, line 1302)
  in call from test_server:run_test_case_eval/9 (test_server.erl, line 1234)
```

Author: ansd

deps/rabbit/test/amqp_client_SUITE.erl

@@ -3006,15 +3006,15 @@ detach_requeues_two_connections(QType, Config) ->
     ok = gen_statem:cast(Session0, {flow_session, #'v1_0.flow'{incoming_window = {uint, 1}}}),
     ok = amqp10_client:flow_link_credit(Receiver0, 50, never),
     %% Wait for credit being applied to the queue.
-    timer:sleep(10),
+    timer:sleep(100),
 
     {ok, Receiver1} = amqp10_client:attach_receiver_link(Session1, <<"receiver 1">>, Address, unsettled),
     receive {amqp10_event, {link, Receiver1, attached}} -> ok
     after 5000 -> ct:fail({missing_event, ?LINE})
     end,
     ok = amqp10_client:flow_link_credit(Receiver1, 40, never),
     %% Wait for credit being applied to the queue.
-    timer:sleep(10),
+    timer:sleep(100),
 
     NumMsgs = 6,
     [begin