test: add solidity test coverage

[ayenesimo1i]

Follow up to this

Added a small bit of coverage to ScrollStandardERC20Factory.sol, ETHRateLimiter.sol and TokenRateLimiter.sol, bringing all three to 100% coverage.

[remingtony31]

Here are some recommendations for the PR on Solidity test coverage:

Error Handling: Ensure tests cover all edge cases, especially unexpected inputs (e.g., invalid addresses, overflow conditions).
Test Clarity: Make test descriptions clear and self-explanatory. Use more descriptive names for test cases, making it easier to understand failures.
Boundary Conditions: Add tests for minimum and maximum input values to ensure the contract handles limits well.
Code Coverage Report: Consider adding a code coverage report to track how much of the codebase is covered by tests.