Service Desk Customers will count towards jira-users license if "Default Group Memberships" is configured

When Default Group Membership is enabled for JIRA to LDAP or Crowd, new users will be automatically added into the configured group(s), usually jira-users so they can login.

In Service Desk 2.0 with public signup, Customers will be added into the configured groups and count towards JIRA license.

Steps to reproduce

1. Configure JIRA to use Crowd for user management
2. Configure Default Group Memberships
3. In JIRA, set Crowd Directory to the top position in Administration >> User management >> User Directories
4. Create Service Desk with public signup
5. Configure email in Service Desk >> Settings >> Email settings
6. Customer to send email to Service Desk

Expected behavior

• Customer does not belong to any groups in JIRA but appear under Service Desk >> People >> Customers
• Customer cannot login JIRA

Actual behavior

• Customer belongs to jira-users group in JIRA
• Customer is now able to login JIRA.