Revert "test: mark test_buffer/test_finalizer flaky"

This reverts commit 73d8db8.

PR-URL: #43418
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

Author: mcollina

test/node-api/node-api.status

@@ -5,6 +5,5 @@ prefix node-api
 # sample-test                        : PASS,FLAKY
 
 [true] # This section applies to all platforms
-test_buffer/test_finalizer : PASS,FLAKY
 
 [$system==win32]