Update MCP Trigger Instrumentation to New Semantic Conventions

[RohitRanjanMS]

Description

The MCP semantic conventions have been updated. Update the trigger instrumentation to match the latest spec.
Tasks

• Review new MCP semantic conventions
• Update attribute names, structure, and required fields

https://opentelemetry.io/docs/specs/semconv/gen-ai/mcp/

[liliankasem]

@RohitRanjanMS I had copilot take a stab at this one, let me know what you think: #197