fix: add missing variables for drain module

enos/enos-scenario-upgrade.hcl

@@ -417,12 +417,21 @@ scenario "upgrade" {
   step "drain_client" {
     depends_on = [step.upgrade_second_client]
 
-    description = <<-EOF 
+    description = <<-EOF
     Selects one client to drain, waits for all allocs to be rescheduled and
     brings back the node eligibility
     EOF
 
     module = module.drain_client
+    variables {
+      # connecting to the Nomad API
+      nomad_addr     = step.provision_cluster.nomad_addr
+      ca_file        = step.provision_cluster.ca_file
+      cert_file      = step.provision_cluster.cert_file
+      key_file       = step.provision_cluster.key_file
+      nomad_token    = step.provision_cluster.nomad_token
+      nodes_to_drain = 1
+    }
   }
 
   step "upgrade_third_client" {