This reverts commit f2823886.

Reason for revert: Causes TSAN timeouts in RestoreHeapLimit, see https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20TSAN/26812

Original change's description:
> [heap] Clean up Heap::ConfigureHeap
> 
> This re-arranges the implementation of the function to make it more
> consistent. The only functional change is replacement of RoundUp with
> RoundDown, which makes more sense for the limits.
> 
> Bug: v8:9306
> Change-Id: Id1d4bc6cc414e3618c3878de8cb87a9ed59711f5
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1643432
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61997}

TBR=ulan@chromium.org,mlippautz@chromium.org,jgruber@chromium.org

Change-Id: I635d60fdfb332cf62ab55eb32242937ebee2f6ad
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9306
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1645323Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61999}