Launch PartitionAllocWithAdvancedChecks (MiracleObject) on Browser UI

Enabling the feature by default. Fixing some unit test failures.

Bug: 351974425
Change-Id: I63d7522907fe459da035c8e0ddf2c5b27425551a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7761746
Reviewed-by: Stephen Nusko <nuskos@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Arthur Sonzogni <arthursonzogni@chromium.org>
Commit-Queue: Mikihito Matsuura <mikt@google.com>
Cr-Commit-Position: refs/heads/main@{#1629854}
NOKEYCHECK=True
GitOrigin-RevId: 34c2ad416612c80386e0662b1cfb5e5425210b8a