nginx fix prod

Fix this issue during the prod deployment

TASK [galaxy nginx | Install prerequisite for openssl_certificate module] ******
fatal: [192.168.16.204]: FAILED! => {"msg": "The conditional check 'galaxy_frontend_create_self_signed_cert' failed. The error was: error while evaluating conditional (galaxy_frontend_create_self_signed_cert): 'galaxy_frontend_create_self_signed_cert' is undefined\n\nThe error appears to have been in '/home/gitlab-runner/builds/Jz4gs41A/0/ifb-elixirfr/usegalaxy-fr/infrastructure/playbook_galaxy-nginx.yml': line 59, column 10, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n  pre_tasks:\n       - name: galaxy nginx | Install prerequisite for openssl_certificate module\n         ^ here\n"}