chore(deps) move from v2-testnet-contracts to zksync-contracts

[coffeexcoin]

PR-Codex overview

This PR focuses on updating the submodules in the project. It removes the lib/v2-testnet-contracts submodule and adds a new submodule for lib/zksync-contracts, reflecting a change in dependencies.

Detailed summary

• Deleted the submodule lib/v2-testnet-contracts.
• Added a new submodule lib/zksync-contracts with its path and URL.
• Updated remappings.txt to include a mapping for era-contracts.
• Modified .gitmodules to reflect the new submodule configuration.

✨ Ask PR-Codex anything about this PR by commenting with /codex {your question}