fix: remove topP parameter from Bedrock inference config

[daniel-lxs]

Fixes #8377

Changes

• Removed topP from BedrockInferenceConfig interface
• Removed topP assignment in createMessage() method
• Removed topP assignment in completePrompt() method

Testing

✅ All 107 Bedrock tests pass including reasoning tests
✅ Type checking passed
✅ Linting passed

Description

The topP parameter was being sent to AWS Bedrock even when extended thinking was enabled, which could cause issues. This PR completely removes the topP parameter from the inference configuration, allowing the provider to rely solely on maxTokens and temperature parameters for both streaming and non-streaming requests.

---

Important

Remove topP parameter from Bedrock inference configuration to prevent issues with extended thinking, updating bedrock.ts and related tests.

• Behavior:
  • Removed topP parameter from BedrockInferenceConfig in bedrock.ts.
  • Removed topP assignment in createMessage() and completePrompt() methods in bedrock.ts.
  • Updated tests in bedrock-reasoning.spec.ts to verify topP is not present in payloads.
• Testing:
  • All 107 Bedrock tests pass, including reasoning tests.
  • Type checking and linting passed.

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[roomote]

I found some issues that need attention:

• Removing topP from Bedrock inference config is correct for Bedrock models that reject temperature + top_p together.
• Please ensure tests and any call sites that asserted/relied on topP are updated; see inline comments.
• Note: GitHub shows merge conflicts; a rebase may be required before merge.

[roomote]

[P1] Contract change removes topP from BedrockInferenceConfig. Ensure related tests and any call sites that asserted/relied on topP are updated (e.g., src/api/providers/tests/bedrock-reasoning.spec.ts expectations when thinking is disabled).

[roomote]

[P2] Non-streaming path mirrors streaming config without topP. Consider adding/adjusting a unit test for completePrompt to assert that inferenceConfig does not include topP, to prevent regressions.