[test] Disable asan.test_externref_emjs_dynlink. NFC (#21490)

This test is failing due to a crash in LLVM that was introduced
in llvm/llvm-project#83196.

test/test_core.py

@@ -9563,6 +9563,8 @@ def test_externref(self):
   @requires_node
   @no_wasm2js('wasm2js does not support reference types')
   def test_externref_emjs(self, dynlink):
+    if dynlink and is_sanitizing(self.emcc_args):
+      self.skipTest('https://github.com/llvm/llvm-project/pull/83196')
     self.emcc_args += ['-mreference-types']
     self.node_args += shared.node_reference_types_flags(self.get_nodejs())
     if dynlink: