Makefile: Update to the best practices

The content of `rabbitmq_auth_backend_cache.app.src` is integrated into
the `Makefile`.

While here, move testsuites from `test/src` to `test.

(cherry picked from commit fdcae62b683d675fb6b0b07a8837b58d6e9ee360)

deps/rabbitmq_auth_backend_cache/Makefile

@@ -1,7 +1,23 @@
 PROJECT = rabbitmq_auth_backend_cache
+PROJECT_DESCRIPTION = RabbitMQ Authentication Backend cache
+PROJECT_MOD = rabbit_auth_backend_cache_app
+
+define PROJECT_ENV
+[
+	    {cache_ttl,      15000},
+	    {cache_module,   rabbit_auth_cache_ets},
+	    {cache_module_args, []},
+	    {cached_backend, rabbit_auth_backend_internal},
+	    {cache_refusals, false}
+	  ]
+endef
+
+define PROJECT_APP_EXTRA_KEYS
+	{broker_version_requirements, []}
+endef
 
 DEPS = rabbit_common rabbit
-TEST_DEPS += rabbit rabbitmq_ct_helpers rabbitmq_ct_client_helpers
+TEST_DEPS = rabbitmq_ct_helpers rabbitmq_ct_client_helpers
 
 DEP_EARLY_PLUGINS = rabbit_common/mk/rabbitmq-early-plugin.mk
 DEP_PLUGINS = rabbit_common/mk/rabbitmq-plugin.mk
@@ -13,9 +29,4 @@ ERLANG_MK_REPO = https://github.com/rabbitmq/erlang.mk.git
 ERLANG_MK_COMMIT = rabbitmq-tmp
 
 include rabbitmq-components.mk
-
-# FIXME: Remove rabbitmq_test as TEST_DEPS from here for now.
-TEST_DEPS := $(filter-out rabbitmq_test,$(TEST_DEPS))
-
 include erlang.mk
-

deps/rabbitmq_auth_backend_cache/src/rabbitmq_auth_backend_cache.app.src

@@ -1,13 +0,0 @@
-%% -*- erlang -*-
-{application, rabbitmq_auth_backend_cache,
- [{description, "RabbitMQ Authentication Backend cache"},
-  {vsn, ""},
-  {modules, [rabbit_auth_backend_cache_app]},
-  {registered, []},
-  {mod, {rabbit_auth_backend_cache_app, []}},
-  {env, [{cache_ttl,      15000},
-         {cache_module,   rabbit_auth_cache_ets},
-         {cache_module_args, []},
-         {cached_backend, rabbit_auth_backend_internal},
-         {cache_refusals, false}] },
-  {applications, [kernel, stdlib, rabbit_common]}]}.