This is a reland of 1c56974f

This is a plain reland of the original CL. The original CL was speculatively
reverted, but ended up not being the cause for bot failures.

Original change's description:
> Unconditionally enable snapshot builds and remove 'v8_use_snapshot'
>
> This CL removes 'v8_use_snapshot' and the usages of the implied
> V8_USE_SNAPSHOT define. One test runner unittest was updated to use the
> "asan" variant instead of the now obsolete "no_snap" variant.
>
> Related chromium CL: https://crrev.com/c/1796325.
>
> Bug: v8:8531
> Change-Id: I5da7c9f8e9110fe7bc0f4e4f821bcb7f7d98f927
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1784282
> Commit-Queue: Simon Zünd <szuend@chromium.org>
> Reviewed-by: Tamer Tas <tmrts@chromium.org>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#64290}

TBR=thakis@chromium.org,machenbach@chromium.org,mstarzinger@chromium.org,jgruber@chromium.org,tmrts@chromium.org,szuend@chromium.org

Bug: v8:8531
Change-Id: Id75a802279238138f7aefec62e0b6425a5acc08d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1864649Reviewed-by: Simon Zünd <szuend@chromium.org>
Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64305}