(PE-40373) Add optional upgrade to migration plan

This commit extends the existing migration plan by adding an optional
upgrade step after the migration is complete. If an upgrade version
is specified, the plan will automatically perform an upgrade to the
new version using the peadm::upgrade plan.

plans/migrate.pp

@@ -4,10 +4,13 @@
 #   The existing PE primary server that will be migrated from
 # @param new_primary_host
 #   The new server that will become the PE primary server
+# @param upgrade_version
+#   Optional version to upgrade to after migration is complete
 #
 plan peadm::migrate (
   Peadm::SingleTargetSpec $old_primary_host,
   Peadm::SingleTargetSpec $new_primary_host,
+  Optional[String] $upgrade_version = undef,
 ) {
   peadm::assert_supported_bolt_version()
 
@@ -40,4 +43,12 @@
       restore_type => 'migration',
       input_file => $remote_backup_path,
   })
+
+  if $upgrade_version {
+    run_plan('peadm::upgrade', {
+        primary_host                => $new_primary_host,
+        version                     => $upgrade_version,
+        download_mode              => 'direct',
+    })
+  }
 }