Instead of creating smaller sandboxes when the allocation of the virtual
address space reservation fails, we now create partially-reserved
sandboxes and halve the reservation size until the initialization
succeeds. That way, the unreserved part of the sandbox can still be used
for allocating objects.

Bug: v8:10391
Change-Id: I89a7790ffcda87ab71cc7b7f1101c0a1c3c62829
Cq-Include-Trybots: luci.v8.try:v8_linux64_heap_sandbox_dbg_ng,v8_linux_arm64_sim_heap_sandbox_dbg_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3714241Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Samuel Groß <saelo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81379}