Fix tests and improve test helpers in rabbitmq_tracing

- Replace timer:sleep(100) with await_condition/1 to wait for trace files
  instead of using fixed delays, making tests more reliable
- Remove explicit close_channel calls for managed CT helper channels
- Add http_get_headers/5 helper function following the same pattern
  as http_get/5 and http_get_raw/5, replacing direct req/4 calls
- Use helper function to validate HTTP status codes and return headers
  consistently with the module's existing helper pattern

(cherry picked from commit b606cc0)
(cherry picked from commit a6c74ec)

Author: bas0N

deps/rabbitmq_tracing/test/rabbit_tracing_SUITE.erl

@@ -93,9 +93,10 @@ tracing_test(Config) ->
                       #amqp_msg{props   = #'P_basic'{},
                                 payload = <<"Hello world">>}),
 
-    rabbit_ct_client_helpers:close_channel(Ch),
-
-    timer:sleep(100),
+    rabbit_ct_helpers:await_condition(fun() ->
+        TraceFiles = http_get(Config, "/trace-files/"),
+        lists:any(fun(#{name := Name}) -> Name =:= <<"test.log">> end, TraceFiles)
+    end),
 
     http_delete(Config, "/traces/%2f/test", ?NO_CONTENT),
     [] = http_get(Config, "/traces/%2f/"),
@@ -145,13 +146,14 @@ trace_file_content_type_test(Config) ->
                                             routing_key = <<"key">> },
                       #amqp_msg{props   = #'P_basic'{},
                                 payload = <<"Test message">>}),
-    rabbit_ct_client_helpers:close_channel(Ch),
 
-    timer:sleep(100),
+    rabbit_ct_helpers:await_condition(fun() ->
+        TraceFiles = http_get(Config, "/trace-files/"),
+        lists:any(fun(#{name := Name}) -> Name =:= <<"test-charset.log">> end, TraceFiles)
+    end),
 
     http_delete(Config, "/traces/%2f/test-charset", ?NO_CONTENT),
-    {ok, {{_HTTP, 200, _}, Headers, _Body}} =
-        req(Config, get, "/trace-files/test-charset.log", [auth_header("guest", "guest")]),
+    Headers = http_get_headers(Config, "/trace-files/test-charset.log"),
     ContentType = proplists:get_value("content-type", Headers),
     ?assertEqual(match, re:run(ContentType, "text/plain", [{capture, none}])),
     ?assertEqual(match, re:run(ContentType, "charset=utf-8", [{capture, none}])),
@@ -184,6 +186,15 @@ http_get_raw(Config, Path, User, Pass, CodeExp) ->
     assert_code(CodeExp, CodeAct, "GET", Path, ResBody),
     ResBody.
 
+http_get_headers(Config, Path) ->
+    http_get_headers(Config, Path, "guest", "guest", ?OK).
+
+http_get_headers(Config, Path, User, Pass, CodeExp) ->
+    {ok, {{_HTTP, CodeAct, _}, Headers, ResBody}} =
+        req(Config, get, Path, [auth_header(User, Pass)]),
+    assert_code(CodeExp, CodeAct, "GET", Path, ResBody),
+    Headers.
+
 http_put(Config, Path, List, CodeExp) ->
     http_put_raw(Config, Path, format_for_upload(List), CodeExp).