Currently the function normalizes only old sparse backing stores.
This patch removed the age check to decouple the heuristic from GC.

Change-Id: I9b7f787315b2b8facfa35358143173f7d207c8da
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2846897Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74156}