Switch to use latest CW agent image for ECS tests. (#325)

*Description of changes:*
Switch to use latest CW agent image for ECS tests.

Workflow tests：
Java:
https://github.com/aws-observability/aws-application-signals-test-framework/actions/runs/11960162230
Python:
https://github.com/aws-observability/aws-application-signals-test-framework/actions/runs/11960165997

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

Author: zzhlogin

.github/workflows/java-ecs-test.yml

@@ -132,8 +132,7 @@ jobs:
           if [ "${{ github.event.repository.name }}" = "amazon-cloudwatch-agent" ]; then
             echo CWAGENT_IMAGE_URI="${{ secrets.AWS_ECR_PRIVATE_REGISTRY }}/cwagent-integration-test:${{ github.sha }}" >> $GITHUB_ENV
           else
-            # echo CWAGENT_IMAGE_URI="public.ecr.aws/cloudwatch-agent/cloudwatch-agent:latest" >> $GITHUB_ENV
-            echo CWAGENT_IMAGE_URI="136146983976.dkr.ecr.us-east-1.amazonaws.com/cloudwatch-agent:1.300047.0b872" >> $GITHUB_ENV
+            echo CWAGENT_IMAGE_URI="public.ecr.aws/cloudwatch-agent/cloudwatch-agent:latest" >> $GITHUB_ENV
           fi
 
       - name: Deploy sample app via terraform and wait for the endpoint to come online

.github/workflows/python-ecs-test.yml

@@ -132,8 +132,7 @@ jobs:
           if [ "${{ github.event.repository.name }}" = "amazon-cloudwatch-agent" ]; then
             echo CWAGENT_IMAGE_URI="${{ secrets.AWS_ECR_PRIVATE_REGISTRY }}/cwagent-integration-test:${{ github.sha }}" >> $GITHUB_ENV
           else
-            # echo CWAGENT_IMAGE_URI="public.ecr.aws/cloudwatch-agent/cloudwatch-agent:latest" >> $GITHUB_ENV
-            echo CWAGENT_IMAGE_URI="136146983976.dkr.ecr.us-east-1.amazonaws.com/cloudwatch-agent:1.300047.0b872" >> $GITHUB_ENV
+            echo CWAGENT_IMAGE_URI="public.ecr.aws/cloudwatch-agent/cloudwatch-agent:latest" >> $GITHUB_ENV
           fi
 
       - name: Deploy sample app via terraform and wait for the endpoint to come online