_decode_tool_use was only used when _tool_json_input_buf was found, but we were decoding the entire _content_block after adding _tool_json_input_buf to it. The _content_block overall which could contain non-JSON elements (e.g. {}), causing failures. To fix this, we have removed _decode_tool_use helper function and inlined JSON decoding logic directly into content_block_stop handler in _process_anthropic_claude_chunk, where we only use it to decode _tool_json_input_buf before appending to _content_block.

Patch based on open-telemetry/opentelemetry-python-contrib#3875 with code copied directly from https://github.com/open-telemetry/opentelemetry-python-contrib/blob/v0.54b1/instrumentation/opentelemetry-instrumentation-botocore/src/opentelemetry/instrumentation/botocore/extensions/bedrock_utils.py#L289

Repeated testing in open-telemetry/opentelemetry-python-contrib#3875 to confirm this works

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