Don't wrap with TemporaryClassLoaderContext in OperationExecutor

Currently, method OperationExecutor#executeStatement in sql client will wrap currently with `

sessionContext.getSessionState().resourceManager.getUserClassLoader()`. Actually, it's not necessary. What' worse, 

it'll will cause the exception 'Trying to access closed classloader. Please check if you store xxx'  after quiting sql client. 

The reason is in `ShutdownHookManager`, it will register a hook after jvm shutdown. In `ShutdownHookManager`, it will

create `Configuration`. It will then access `Thread.currentThread().getContextClassLoader()` which is FlinkUserClassLoader, the FlinkUserClassLoader has been closed before. So, it'll then cause `'Trying to access closed classloader` exception.