Orchestrator's `rebase` protection broken due to EIP-7702

[pmerkleplant]

The orchestrator performs a check in rebase() trying to prevent contracts from executing the rebase. IIUC the idea behind this is to prevent sandwiching AMPL's supply adjustment.

ampleforth-contracts/contracts/Orchestrator.sol

Line 44 in 1d13ed3

require(msg.sender == tx.origin); // solhint-disable-line avoid-tx-origin

However, since the Pectra fork launched on Ethereum mainnet it's possible for EOAs to have executable logic, see EIP-7702. This update renders the check mostly useless.