Fix run notifications smoke test variable check

Author: steventux

scripts/terraform/terraform.mk

@@ -76,8 +76,9 @@ terraform-validate: terraform-init-no-backend # Validate Terraform changes - mak
 	terraform -chdir=infrastructure/terraform validate
 
 notifications-smoke-test:
-	$(if ${TF_VAR_run_notifications_smoke_test}, \
-		pip install pytest mesh-client \
-		pytest -vv scripts/python/smoke_test/notifications_smoke_test.py, \
+	@if [[ "${RUN_NOTIFICATIONS_SMOKE_TEST}" == true ]]; then \
+		pip install pytest mesh-client && \
+		pytest -vv scripts/python/smoke_test/notifications_smoke_test.py \
+	else \
 		echo "Notifications smoke test skipped." \
-	)
+	fi