Remove xDai configuration

[rubo]

Changes

• As we renamed xDai to Gnosis more than 7 months ago, it was enough time for users to migrate. Removed obsolete xDai configuration given the recent confusion and issues caused by that
• Removed xDai config tests

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No

Documentation

Requires documentation update

• Yes
• No

Requires explanation in Release Notes

• Yes
• No

⚠️ The xdai configuration moniker is no longer supported. Use gnosis instead.