test: mark test-http-dump-req-when-res-ends as flaky on windows

PR-URL: #30316
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

test/parallel/parallel.status

@@ -19,6 +19,8 @@ test-worker-memory: PASS,FLAKY
 test-http2-client-upload: PASS,FLAKY
 # https://github.com/nodejs/node/issues/20750
 test-http2-client-upload-reject: PASS,FLAKY
+# https://github.com/nodejs/node/issues/30011
+test-http-dump-req-when-res-ends: PASS,FLAKY
 
 [$system==linux]