mark: test-net-write-fully-async-buffer as flaky

Author: aduh95

test/parallel/parallel.status

@@ -12,6 +12,8 @@ test-shadow-realm-gc: SKIP
 test-shadow-realm-gc-module: SKIP
 # https://github.com/nodejs/node/issues/52274
 test-worker-arraybuffer-zerofill: PASS, FLAKY
+# https://github.com/nodejs/node/issues/47428
+test-net-write-fully-async-buffer: PASS,FLAKY
 
 # https://github.com/nodejs/node/issues/51862
 test-fs-read-stream-concurrent-reads: PASS, FLAKY