test: set test-fs-watch as flaky

Ref: #50249

Author: anonrig

test/parallel/parallel.status

@@ -99,3 +99,7 @@ test-http-pipeline-flood: SKIP
 [$asan==on]
 # https://github.com/nodejs/node/issues/39655
 test-cluster-primary-error: PASS, FLAKY
+
+[$arch==s390x]
+# https://github.com/nodejs/node/issues/50249
+test-fs-watch-recursive-add-file-with-url: PASS, FLAKY