async_hooks: don't read resource if ALS is disabled

Only call executionAsyncResource() in getStore() if the ALS instance is
enabled because the resource is not needed otherwise.

PR-URL: https://github.com/nodejs/node/pull/34617


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>