doc: remove "considered" for clarity

"considered undefined" suggests that it's not REALLY undefined. It's
really undefined. Be firm!

PR-URL: nodejs#42218
Reviewed-By: Akhil Marsonya <akhil.marsonya27@gmail.com>
Reviewed-By: Mestery <mestery@protonmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/v8.md

@@ -815,7 +815,7 @@ via the promise hooks mechanism, the `init()`, `before()`, `after()`, and
 promises which would produce an infinite loop.
 
 While this API is used to feed promise events into [`async_hooks`][], the
-ordering between the two is considered undefined. Both APIs are multi-tenant
+ordering between the two is undefined. Both APIs are multi-tenant
 and therefore could produce events in any order relative to each other.
 
 #### `init(promise, parent)`