Follow-up to #60360 and #59016 (cc @NeelChotai @bennetbo).

Claude Sonnet 5 and Claude Fable 5 cannot be invoked with on-demand
throughput — AWS requires an inference profile, and only `us.*` and
`global.*` profiles exist for these models ([Sonnet 5 model
card](https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-anthropic-claude-sonnet-5.html),
[Fable 5 model
card](https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-anthropic-claude-fable-5.html)).

For users in EU/APAC regions without `allow_global` enabled, Zed
generated profile IDs like `eu.anthropic.claude-sonnet-5`, which fail
with:

```
ResourceNotFoundException: Model not found.
```

And falling back to the bare model ID isn't an option either, since
direct invocation fails with:

```
Invocation of model ID anthropic.claude-fable-5 with on-demand throughput isn't supported.
Retry your request with the ID or ARN of an inference profile that contains this model.
```

Confirmed against the live AWS API — only `us.*` and `global.*` profiles
exist:

```
❯ aws bedrock list-inference-profiles --region eu-west-1 \
    --query "inferenceProfileSummaries[?contains(inferenceProfileId, 'sonnet-5') || contains(inferenceProfileId, 'fable')].[inferenceProfileId,status]" \
    --output table
------------------------------------------------
|             ListInferenceProfiles            |
+------------------------------------+---------+
|  global.anthropic.claude-sonnet-5  |  ACTIVE |
|  global.anthropic.claude-fable-5   |  ACTIVE |
+------------------------------------+---------+
```

This change removes both models from the EU match arm and routes them
through the global inference profile when no regional profile is
available. US regions continue to use the `us.*` profile. Verified
working from `eu-west-1`.

Note: this means requests from non-US regions route through the global
profile, which may dispatch inference to any supported AWS region.
That's inherent to how AWS exposes these models — there is no
EU-resident option today.

Release Notes:

- Fixed Claude Sonnet 5 and Claude Fable 5 failing on Amazon Bedrock in
non-US regions.

---------

Co-authored-by: Neel <neel@zed.dev>