Temporarily disable test_exceptions_longjmp3_wasm under LSan. NFC (#17006)

This test currently has a leak: #17004.

Author: sbc100

tests/test_core.py

@@ -1738,6 +1738,8 @@ def test_exceptions_longjmp2(self):
 
   @with_both_eh_sjlj
   def test_exceptions_longjmp3(self):
+    if '-fwasm-exceptions' in self.emcc_args:
+      self.skipTest('https://github.com/emscripten-core/emscripten/issues/17004')
     self.do_core_test('test_exceptions_longjmp3.cpp')
 
   @with_both_eh_sjlj