Amazon Bedrock Agent Samples - Adding OTEL tracing to `bedrock_agent_helper.py`

[fredjoonpark]

Describe the improvement request

Add support for OTEL tracing from event stream for bedrock agents in bedrock_agent_helper.py to demo example of multi-agent observability (with OpenLLMetry)

What are your suggestions?

Define toggle-enabled OTEL tracing and spans when working with bedrock agents via the helper as to allow standardized tracing for use with observability and monitoring.

Describe alternatives you've considered

There is an open issue in OpenLLMetry that adds native support for instrumentation of Bedrock agents.