Configure registrar to use MySQL 8.0 in devstack

[iamsobanjaved]

As we are in the process of upgrading the version of MySQL on our every environment, so for the first step we want our devstack to use MySQL 8 with credentials service and all its provisioning scripts

### A/C
- [ ] Change container dependency to MySQL 8
- [ ] Set the default host to MySQL 8
- [ ] Update provisioning script to use Mysql 8
- [ ] Check if the change is needed in the `dev.pull` command
- [ ] Update devstack configuration YAML file.
- [ ] Test service with MySQL 8 and make sure the data remains intact.