Remove KAIRO exporter from .env.template

Author: Yogeshp-MSFT

python/google-adk/sample-agent/.env.template

@@ -112,7 +112,6 @@ LOG_LEVEL=INFO
 # -----------------------------------------------------------------------------
 ENABLE_OBSERVABILITY=true
 ENABLE_A365_OBSERVABILITY_EXPORTER=false
-ENABLE_KAIRO_EXPORTER=false
 PYTHON_ENVIRONMENT=development
 OBSERVABILITY_SERVICE_NAME=GoogleADKSampleAgent
 OBSERVABILITY_SERVICE_NAMESPACE=GoogleADKTesting