fix clean.yml, env_vars in 'Make config variables lowercase'

clean.yml

@@ -12,5 +12,5 @@
         - "roles/main_infra/files/backend.tfvars"
         - "roles/main_infra/files/terraform.tfplan"
         - "log.txt"
-        - "blockscout-*"
-        - "/tmp/files-*"
+        - "/tmp/blockscout-{{ group_names[0] }}-{{ chain }}"
+        - "/tmp/files-{{ group_names[0] }}"

roles/main_software/tasks/main.yml

@@ -80,7 +80,7 @@
   set_fact:
     lower_env: "{{ lower_env | combine ({item.key|lower : item.value})  }}"
   with_dict: "{{ env_vars }}"
-  when: env_vars|length > 0
+  when: env_vars is defined
   vars:
     lower_env: {}
   tags: