[wasm] Disable test-run-wasm/I64ShlOnDifferentRegisters test

The tests are flaky at the moment.

CC=clemensh@chromium.org
R=machenbach@chromium.org

No-Try: true
Change-Id: Ifc56116ebbe44d92c726c973e2beb8a1ec996379
Reviewed-on: https://chromium-review.googlesource.com/995092Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52342}

test/cctest/cctest.status

@@ -133,6 +133,10 @@
   'test-serialize/StartupSerializerTwice': [SKIP],
   'test-serialize/StartupSerializerOnceRunScript': [SKIP],
   'test-serialize/StartupSerializerTwiceRunScript': [SKIP],
+
+  # Flaky test
+  'test-run-wasm/RunWasmLiftoff_I64ShrSOnDifferentRegisters': [SKIP],
+  'test-run-wasm/RunWasmTurbofan_I64ShlOnDifferentRegisters': [SKIP],
 }],  # ALWAYS
 
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