Automatic Arrayification for partition alloc

This is the result of arrayification in the partition alloc library, the first step towards spanification.

Change-Id: I94d65a917bbd9a4133e822131a6c94eebac5c06e
Bug: 501143531
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/8037246
Reviewed-by: Stephen Nusko <nuskos@chromium.org>
Commit-Queue: Daniel Angulo <angdaniel@google.com>
Cr-Commit-Position: refs/heads/main@{#1658083}
NOKEYCHECK=True
GitOrigin-RevId: 43305f687a7ace0ce9c49bd6d406012d10324573