refactor(jenkins): remove Docker agent in favor of agent any

Replace Docker-based agent configuration with `agent any` to align
with the quickstart-tutorials approach where Jenkins agents are
pre-configured with necessary tools via docker-compose infrastructure.

This change simplifies the Jenkinsfile and delegates infrastructure
concerns (like port mapping) to the deployment environment.

Author: gounthar

jenkins/Jenkinsfile

@@ -1,10 +1,5 @@
 pipeline {
-    agent {
-        docker {
-            image 'node:lts-buster-slim'
-            args '-p 3000:3000'
-        }
-    }
+    agent any
     environment {
         CI = 'true'
     }

jenkins/scripts/deliver.sh

@@ -25,5 +25,3 @@ set +x
 
 echo 'Now...'
 echo 'Visit http://localhost:3000 to see your Node.js/React application in action.'
-echo '(This is why you specified the "args ''-p 3000:3000''" parameter when you'
-echo 'created your initial Pipeline as a Jenkinsfile.)'