[wasm] Skip test in multiple isolates

If both isolates run this test, they are kind of racing on the
{tier_down_} flag, hence you get unexpected results.

Bug: v8:10189, v8:10099
Change-Id: I8657c32c024898442d5c916cf15077c846276b1f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2044544
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66188}

test/debugger/debugger.status

@@ -149,4 +149,11 @@
   'debug/wasm/frame-inspection': [SKIP],
 }],
 
+##############################################################################
+['isolates', {
+  # Tier down/up Wasm NativeModule in debugging is non-deterministic with
+  # multiple isolates (https://crbug.com/v8/10099).
+  'debug/wasm/debug-enabled-tier-down-wasm': [SKIP],
+}],  # 'isolates'
+
 ]