fix(user.sls): fix `salt-lint` errors

```bash
Examining mysql/user.sls of type state
[202] Jinja statement should have spaces before and after: {% statement %}
mysql/user.sls:35
{% set state_id = 'mysql_user_' ~ name ~ '_' ~ host%}

[206] Jinja variables should have spaces before and after: {{ var_name }}
mysql/user.sls:100
    - grant: {{db['grants']|join(",")}}
```