fix: Standardize Chain Names and Clean Up Bridge Definitions

[0xsenty]

Hi team,

I went ahead and tackled the TODO: FIX need to control chain naming here in the bridge network definitions.

Here's what I did:

• Standardized all chain names to lowercase throughout the file (chains, destinationChain, chainMapping keys/values). This resolves the inconsistency we had.
• Cleaned up the chainMapping objects, removing mappings that were no longer needed after standardizing (like avalanche: "avax"). Only the essential mappings remain.
• Removed the large commented-out sections of old bridges to keep the file cleaner.
• Fixed a few duplicate chain entries within the chains arrays.

This should make the configuration much more consistent and reliable to work with.