test: mark test-child-process-execfile flaky

Refs: #25029

PR-URL: #25051
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Richard Lau <[email protected]>

Author: Trott

test/parallel/parallel.status

@@ -5,6 +5,8 @@ prefix parallel
 # sample-test                        : PASS,FLAKY
 
 [true] # This section applies to all platforms
+# https://github.com/nodejs/node/issues/25029
+test-child-process-execfile: PASS,FLAKY
 # https://github.com/nodejs/node/issues/23207
 test-net-connect-options-port: PASS,FLAKY
 # https://github.com/nodejs/node/issues/25033