ci: fix commit id

Author: necipallef

.github/workflows/e2e_test_for_prs.yml

@@ -25,8 +25,7 @@ jobs:
 #          aws ssm put-parameter --name "/cloudfront-integration-e2e/branch_name" --value "${{github.head_ref}}" --type "String" --overwrite
       - name: Trigger AWS CodePipeline
         run: |
-          git status
-          git_hash=$(git rev-parse --short "$GITHUB_SHA")
+          git_hash=${{ github.event.pull_request.head.ref }}
           echo $git_hash
           codepipeline_execution_id=$(aws codepipeline start-pipeline-execution --name ${{vars.AWS_E2E_TOPIC_BRANCH_CODEPIPELINE_NAME}} --source-revisions actionName=Source,revisionType=COMMIT_ID,revisionValue=$git_hash --query 'pipelineExecutionId' --output text)
           echo "Pipeline execution ID: $codepipeline_execution_id"