test: mark test-cli-syntax as flaky/unreliable

Refs: nodejs#24403

PR-URL: nodejs#24957
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

test/sequential/sequential.status

@@ -7,6 +7,8 @@ prefix sequential
 [true] # This section applies to all platforms
 # https://github.com/nodejs/node/issues/22336
 test-gc-http-client: PASS,FLAKY
+# https://github.com/nodejs/node/issues/24403
+test-cli-syntax: PASS,FLAKY
 
 [$system==win32]
 # https://github.com/nodejs/node/issues/22327