[test] Skip flaky test

TBR=mslekova@chromium.org

No-Try: true
Bug: v8:10647
Change-Id: I177abffb3286703df110f1875c70ac1120d07595
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2270541Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68562}

test/mjsunit/mjsunit.status

@@ -844,6 +844,9 @@
   # Tier down/up Wasm NativeModule in debugging is non-deterministic with
   # multiple isolates (https://crbug.com/v8/10099).
   'wasm/tier-down-to-liftoff': [SKIP],
+
+  # https://crbug.com/v8/10647
+  'wasm/compare-exchange64-stress': [SKIP],
 }],  # 'isolates'
 
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