Disable another static analysis rule (dotnet/corefx#42265)

Signed-off-by: dotnet-bot <dotnet-bot@microsoft.com>

netcore/System.Private.CoreLib/shared/CodeAnalysis.ruleset

@@ -52,6 +52,7 @@
     <Rule Id="CA1822" Action="None" /> <!-- Mark members as static -->
     <Rule Id="CA1827" Action="None" /> <!-- Do not use Count() when Any() can be used -->
     <Rule Id="CA2000" Action="None" /> <!-- Dispose objects before losing scope -->
+    <Rule Id="CA2002" Action="None" /> <!-- Do not lock on objects with weak identity -->
     <Rule Id="CA2010" Action="None" /> <!-- Always consume the value returned by methods marked with PreserveSigAttribute -->
     <Rule Id="CA2100" Action="None" /> <!-- Review SQL queries for security vulnerabilities -->
     <Rule Id="CA2101" Action="None" /> <!-- Specify marshaling for P/Invoke string arguments -->