This reverts commit 7ef67b2e.

Reason for revert: Speculative revert for a blocked roll - https://chromium-review.googlesource.com/c/chromium/src/+/2947365

Original change's description:
> heap: Fix initial GC configuration for C++-only heaps
>
> Heaps in V8 start with a large limit that is shrunk upon young
> generation GCs, based on some liveness estimate. This provides best
> throughput during startup while at the same time finding a reasonable
> first limit.
>
> For C++ (embedder memory) there is no estimate which is why it was
> piggy-backing on V8. This breaks in scenarios where no JS memory is
> allocated.
>
> In this fix we start a memory reducer after embedder memory has hit
> the activation threshold if no GC happened so far. As soon as a single
> Scavenger has happened, we leave it up to the JS estimate to figure
> out a limit. Memory reducing GCs will then find a regular limit based
> on the initial live size.
>
> Drive-by: Give embedders the same activiation threshold of 8MB as JS.
>
> Bug: chromium:1217076
> Change-Id: I8469696002ac2af8d75d6b47def062d2608387a1
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2944935
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#75012}

Bug: chromium:1217076
Change-Id: Ic1530162e846c2a767ea5ea902a01a21967d8e35
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2947419
Auto-Submit: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#75034}