[sandbox] Skip mkgrokdump test in non-sandbox mode

When the sandbox is disabled, object layouts are now different as
ExternalPointerSlots are then 64-bit (raw pointers) instead of 32-bit
(ExternalPointerHandles).

Bug: v8:10391
Change-Id: Ia03d1ae9300fad96e40b77f0ed9544a1a118b74a
Cq-Include-Trybots: luci.v8.try.triggered:v8_linux64_no_sandbox_dbg_ng_triggered
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3884075Reviewed-by: Igor Sheludko <ishell@chromium.org>
Auto-Submit: Samuel Groß <saelo@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Samuel Groß <saelo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83089}

test/mkgrokdump/mkgrokdump.status

@@ -5,8 +5,8 @@
 [
 
 # Only test for default mode x64.
-['variant != default or arch != x64 or lite_mode or not pointer_compression', {
+['variant != default or arch != x64 or lite_mode or not pointer_compression or not sandbox', {
   '*': [SKIP],
-}],  # variant != default or arch != x64 or lite_mode
+}],  # variant != default or arch != x64 or lite_mode or not pointer_compression or not sandbox
 
 ]