feat: add the possibility to override the default application secret prefix...

feat: add the possibility to override the default application secret prefix with custom in order to support multiple secrets in monorepo deployments.

If you have a monorepo project, you can only prefix your secrets with K8S_SECRET_, and all the applications inside that repository will share the same secret. To separate each secret per application inside monorepo we need a custom secret prefix. That is achieved by adding the variable APPLICATION_SECRET_PREFIX_REGEX at the job level inside .gitlab-ci.yml file for each deployment. This is optional, and in case the variable is not set, everything will work as it did before.