Fix appointment-service availability issues (50% error rate)

[github-actions]

Summary

Fixes critical availability issue in appointment-service-get Lambda function that was causing 50% error rate.

Changes

1. Fixed Lambda Code

File: lambda-petclinic/sample-apps/function3-different-version/lambda_function.py

• Removed hardcoded exception trigger at line 26-27 that was causing NullPointerException
• Also fixed typo in error message (line 30)

2. Route Traffic to Stable Version

File: lambda-petclinic/cdk/lib/lambda-petclinic-stack.ts

• Changed alternateVersionWeight from 0.5 to 0 (line 208)
• Routes 100% traffic to stable v1 version instead of 50/50 split

Root Cause

The buggy alternate version contained intentional failure code:

if pet_id == "111111111111":
    raise Exception('Fail to parse the request. Cause: NullPointerException')

With 50% traffic split, this caused 50% error rate (3,148 errors in 24h period).

Impact

• Eliminates 50% error rate in appointment-service-get Lambda
• Resolves NullPointerException errors
• Restores 100% availability for appointment queries

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