audit: TimelockExecutionStrategy Deployed as Proxy at Risk From Implementation SELFDESTRUCT

[Orland0x]

It is expected that TimelockExecutionStrategy will be deployed as a proxy contract. However, it is critical that the implementation contract shared by the proxies is disabled, and cannot execute transactions. If the base implementation contract is in operation, a transaction could perform a delegate call into a contract containing the SELFDESTRUCT opcode, irrecoverably disabling all the proxies using that implementation.