test: remove flaky designation for test_threadsafe_function

The test_threadsafe_function doesn't seem to be flaky anymore on
Windows. Optimistically removing the flaky designation in the relevant
status file.

Refs: #23621 (comment)

PR-URL: #26403
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: Richard Lau <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>

Author: Trott

Diff for: test/node-api/node-api.status

@@ -7,5 +7,3 @@ prefix node-api
 [true] # This section applies to all platforms
 
 [$system==win32]
-# https://github.com/nodejs/node/issues/23621
-test_threadsafe_function/test: PASS,FLAKY