copr: fixup aws volume config

roles/copr/backend/files/provision/builderpb-aws-aarch64.yml

@@ -16,6 +16,11 @@
     max_spawn_time: 1100
     spawning_vm_user: "fedora"
     arch: aarch64
+    instance_volumes:
+      - device_name: sdb
+        delete_on_termination: True
+        volume_type: gp2
+        volume_size: 100
 
   tasks:
   - include: "spinup_aws_task.yml"

roles/copr/backend/files/provision/builderpb-aws-x86_64.yml

@@ -16,11 +16,6 @@
     max_spawn_time: 1100
     spawning_vm_user: "fedora"
     arch: x86_64
-    instance_volumes:
-      - device_name: sdb
-        delete_on_termination: True
-        volume_type: gp2
-        volume_size: 100
 
   tasks:
   - include: "spinup_aws_task.yml"

roles/copr/backend/files/provision/spinup_aws_task.yml

@@ -17,7 +17,7 @@
       arch: "{{ arch }}"
     aws_access_key: "{{ aws_access_key }}"
     aws_secret_key: "{{ aws_secret_key }}"
-    volumes: "{{ instance_volumes or [] }}"
+    volumes: "{% if instance_volumes is defined %}{{ instance_volumes }}{% else %}[]{% endif %}"
   register: ec2
 
 - name: Add new instance to host group