Do not evict a contract from within a call stack

We don't want to trigger contract eviction automatically when
a contract is called. This is because those changes can be
reverted due to how storage transactions are used at the moment.
More Information:
https://github.com/paritytech/substrate/issues/6439#issuecomment-648754324

It can be re-introduced once the linked issue is resolved. In the meantime
`claim_surcharge` must be called to evict a contract.