Test config/ package correctly

For directories that have no binary artifacts, it is easier to let
"go test" find them, rather than having Makefile there.

The previous structure was the reason we didn't run "go test" against
config/ package.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

Author: Kazuyoshi Kato

Makefile

@@ -11,7 +11,7 @@
 # express or implied. See the License for the specific language governing
 # permissions and limitations under the License.
 
-SUBDIRS:=agent runtime internal examples firecracker-control/cmd/containerd eventbridge
+SUBDIRS:=agent runtime examples firecracker-control/cmd/containerd
 TEST_SUBDIRS:=$(addprefix test-,$(SUBDIRS))
 INTEG_TEST_SUBDIRS:=$(addprefix integ-test-,$(SUBDIRS))
 
@@ -121,6 +121,7 @@ image: $(RUNC_BIN) agent-in-docker
 	$(MAKE) -C tools/image-builder all-in-docker
 
 test: $(TEST_SUBDIRS)
+	go test ./... $(EXTRAGOARGS)
 
 # test-in-docker runs all unit tests inside a docker container. Use "integ-test" to
 # run the integ-tests inside containers.