At least for the initial rollout, we will gracefully handle cage
reservation failures by shrinking the size of the cage until the
reservation succeeds or the size drops below the mimimum cage size. This
will allow collecting statistics on how often cage reservation failures
occur in practice for different cage sizes, which will in turn influence
the decision on how to handle them in the future.

Bug: chromium:1218005
Change-Id: Ica58951ba51ac01bc2c387b34dfc8d9051ed4d75
Cq-Include-Trybots: luci.v8.try:v8_linux64_heap_sandbox_dbg_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3168347Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Samuel Groß <saelo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76948}