Update env variable name for automated test sender (#1490)

* Update env variable name and key for automated test sender

* Updated env variable name

* Added pull_request trigger for testing

* Removed pull_request trigger

.github/workflows/automated-staging-test-submit.yml

@@ -23,7 +23,7 @@ jobs:
 
       - name: Write private key to file
         run: |
-          echo "${{ secrets.AUTOMATED_STAGING_RS_INTEGRATION_PRIVATE_KEY }}" > /tmp/staging_private_key.pem
+          echo "${{ secrets.SIMULATED_SENDER_STAGING_PRIVATE_KEY }}" > /tmp/staging_private_key.pem
           chmod 600 /tmp/staging_private_key.pem
 
       - name: Send HL7 sample messages to staging RS