test: mark test-cluster-primary-error as flaky on macOS

Author: F3n67u

test/parallel/parallel.status

@@ -23,6 +23,8 @@ test-fs-rmdir-recursive: PASS, FLAKY
 test-domain-error-types: PASS,FLAKY
 
 [$system==macos]
+# https://github.com/nodejs/node/issues/39655
+test-cluster-primary-error: PASS, FLAKY
 # https://github.com/nodejs/node/issues/42741
 test-http-server-headers-timeout-keepalive: PASS,FLAKY
 test-http-server-request-timeout-keepalive: PASS,FLAKY