Enhance Testing Coverage for Chainlink Feeds and Factory

[TomasCImach]

          The changes proposed here tests the cases with an already deployed feed factory and feed. While this is very helpful and enable us to test on Arbitrum mainnet environment with the actual feeds that we're using, it will not catch the future changes made on chainlink feeds and fatory.

We should add test-deployed feeds as well.
@EperezOk @magnetto90 please comment on this.

Originally posted by @TomasCImach in #133 (comment)

[EperezOk]

If we are going to write new tests, I think we should do that in Foundry. However, unless we plan on making changes to the feeds/factory, I don't think this is a priority right now.