Require pointer_compression_shared_cage for virtual_memory_cage

The shared pointer compression cage is a requirement for the V8 virtual
memory cage, and there are some configurations that don't enable the
former but enable the latter, which thus break.

Bug: chromium:1218005
Change-Id: I734598a952ccafd57e4ed63a71e76e4dc252057e
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/+/3211996Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Samuel Groß <saelo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77305}

BUILD.gn

@@ -476,8 +476,7 @@ if (build_with_chromium && v8_current_cpu == "arm64" &&
 }
 
 # Enable the virtual memory cage on 64-bit Chromium builds.
-if (build_with_chromium &&
-    (v8_current_cpu == "arm64" || v8_current_cpu == "x64")) {
+if (build_with_chromium && v8_enable_pointer_compression_shared_cage) {
   # The cage is incompatible with lsan.
   v8_enable_virtual_memory_cage = !is_lsan
 }