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}