test: mark WASI's test-return-on-exit as flaky

Refs: https://github.com/nodejs/node/pull/36139

PR-URL: https://github.com/nodejs/node/pull/36139
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>

test/wasi/wasi.status

@@ -5,3 +5,7 @@ prefix wasi
 # sample-test                        : PASS,FLAKY
 
 [true] # This section applies to all platforms
+
+[$system==win32]
+# https://github.com/nodejs/node/pull/36139
+test-return-on-exit: PASS,FLAKY