build: only run controller-gen on actual API dirs

Author: dkoshkin

api/external/sigs.k8s.io/cluster-api-addon-provider-helm/api/v1alpha1/zz_generated.deepcopy.go

@@ -179,7 +179,7 @@ go-generate: ; $(info $(M) running go generate)
 	go generate -x ./...
 	controller-gen paths="./..." rbac:headerFile="hack/license-header.yaml.txt",roleName=capi-runtime-extensions-manager-role output:rbac:artifacts:config=charts/capi-runtime-extensions/templates
 	sed --in-place 's/capi-runtime-extensions-manager-role/{{ include "chart.name" . }}-manager-role/' charts/capi-runtime-extensions/templates/role.yaml
-	controller-gen paths="./api/..." object:headerFile="hack/license-header.go.txt" output:object:artifacts:config=/dev/null
+	controller-gen paths="./api/v1alpha1/..." object:headerFile="hack/license-header.go.txt" output:object:artifacts:config=/dev/null
 	$(MAKE) go-fix
 
 .PHONY: go-mod-upgrade