bedrock: Fix cross-region inference

[5herlocked]

Closes #30535

Release Notes:

• Add support for Meta Llama 4 Scout and Maverick models
• Fixed cross-region inference for all regions
• Updated all models available through Cross Region inference

[Qkessler]

Just tested this with using gh pull successfully with the following settings:

 "language_models": {
    "bedrock": {
      "authentication_method": "named_profile",
      "region": "eu-central-1",
      "profile": "bedrock-access"
    }
  },
  "agent": {
    "version": "2",
    "dock": "bottom",
    "default_profile": "write",
    "default_model": {
      "provider": "amazon-bedrock",
      "model": "anthropic.claude-3-7-sonnet-20250219-v1:0"
    }
  },

Haven't yet been able to make it work with Sonnet 3.5 v2, though. For now, it's good enough. I'd really appreciate if documentation around setting up the Bedrock provider was part of the Website. Discoverability is key for new features like this one.

[5herlocked]

@Qkessler #31043 has updates to the documentation please do look it over and suggest changes if you have improvements!