test: use `emqx_cth_suite` in `emqx_coap_api_SUITE`

`emqx_coap_api_SUITE` was failing with `emqx_authn_schema_not_injected`
(missing authn schema mods in persistent_term) if it was run standalone.

apps/emqx_gateway_coap/test/emqx_coap_api_SUITE.erl

@@ -57,14 +57,22 @@ all() ->
 
 init_per_suite(Config) ->
     application:load(emqx_gateway_coap),
-    ok = emqx_common_test_helpers:load_config(emqx_gateway_schema, ?CONF_DEFAULT),
-    emqx_mgmt_api_test_util:init_suite([emqx_auth, emqx_gateway]),
-    Config.
+    Apps = emqx_cth_suite:start(
+        [
+            {emqx_conf, ?CONF_DEFAULT},
+            emqx_gateway,
+            emqx_auth,
+            emqx_management,
+            {emqx_dashboard, "dashboard.listeners.http { enable = true, bind = 18083 }"}
+        ],
+        #{work_dir => emqx_cth_suite:work_dir(Config)}
+    ),
+    _ = emqx_common_test_http:create_default_app(),
+    [{suite_apps, Apps} | Config].
 
 end_per_suite(Config) ->
-    {ok, _} = emqx:remove_config([<<"gateway">>, <<"coap">>]),
-    emqx_mgmt_api_test_util:end_suite([emqx_gateway, emqx_auth]),
-    Config.
+    emqx_cth_suite:stop(?config(suite_apps, Config)),
+    emqx_config:delete_override_conf_files().
 
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