feat(v2): allow disabling Anthropic thinking block binding

[DEAN-Cherry]

Fixes #48757

Issue for this PR

Type of change

• Bug fix
• New feature

What does this PR do?

V2 supports the V1-compatible blockBinding opt-out.

How did you verify your code works?

Tests and typechecks pass.

Screenshots / recordings

Not applicable.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

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[github-actions]

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