test: un-set test-emit-after-on-destroyed as flaky

I tested running the test case 100k times on the AIX ci machine
and was unable to re-produce the error. Also it has not showed up
recently as flaky on the ci. I suggest we mark this
as un-flaky.

ref: nodejs#50245 (comment)
PR-URL: nodejs#51995
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/async-hooks/async-hooks.status

@@ -21,5 +21,3 @@ test-callback-error: PASS, FLAKY
 [$system==freebsd]
 
 [$system==aix]
-# https://github.com/nodejs/node/issues/50245
-test-emit-after-on-destroyed: PASS, FLAKY