test: remove test-file-write-stream4 flaky designation

Recent failures seem to be only caused by insufficient space left on the
device.

PR-URL: #51472
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Debadree Chatterjee <debadree333@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>

test/parallel/parallel.status

@@ -26,8 +26,6 @@ test-worker-nearheaplimit-deadlock: PASS, FLAKY
 [$system==linux]
 # https://github.com/nodejs/node/issues/39368
 test-domain-error-types: PASS,FLAKY
-# https://github.com/nodejs/node/issues/47420
-test-file-write-stream4: PASS,FLAKY
 # https://github.com/nodejs/node/issues/43465
 test-http-server-request-timeouts-mixed: PASS, FLAKY