[mjsunit] Skip OOM test on Arm64

Adding two small builtins pushed this test over the OOM threshold,
so we disable it for now.

Bug: v8:9488
Change-Id: I6c0696c260cd8ef9e6ee59caec4848aab439fdf2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1706049Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62783}

test/mjsunit/mjsunit.status

@@ -783,6 +783,7 @@
   'regress/regress-748069': [FAIL],
   'regress/regress-752764': [FAIL],
   # Flaky OOM:
+  'regress/regress-779407': [SKIP],
   'regress/regress-852258': [SKIP],
 }],  # 'system == android'