GitLab QA: Add GITLAB_USER_TYPE to support different login types (e.g. standard, LDAP)
GITLAB_USERNAME and GITLAB_PASSWORD may be specified for an LDAP login, but QA scenarios may need to know which type it is in order to log in successfully.
GITLAB_USERNAME and GITLAB_PASSWORD may be specified for an LDAP login, but QA scenarios may need to know which type it is in order to log in successfully.