Removal of Nonce in Part A of EIP-7702 Gas Sponsorship Guide

[IchiBera]

The nonce within excecute() is not used within this guide's Part A. It was initially there because it was thought to have nonce management within Part A.

Since Part B handles this now, the nonce aspect does not need to be included in Part A. That said, it is still useful to walk through to understand nonce management.

For now, we will keep the nonce in Part A due to time constraints. This issue is to mark that we will remove it from Part A to streamline the guide more.

Reference: PR #119