test: add invalid config chainWriter tests

[maximopalopoli]

What Changed?

The goal is to increase the test coverage of chain writer, by testing those cases of passing an invalid config so the contracts addresses are set as nil and the initial validations of the methods will fail.

Increases test coverage of chainio/clients/elcontracts/writer.go up to 79.2%.

Reviewer Checklist

• Code is well-documented
• Code adheres to Go naming conventions
• Code deprecates any old functionality before removing it

[damiramirez]

Left some comments regarding the address values. I think it would be better to use constants instead of literals when we know the addresses come from Anvil.

[MegaRedHand]

LGTM