OP-5530 - Fix potentially bad permissions on /opt/rbenv

This PR fixes a situation where /opt/rbenv exists, but /opt/rbenv/.git (and other directories) have root:root permissions.  This causes the rbenv cookbook to fail and ultimately fail a node to be cleanly provisioned on AWS.

/cc @zendesk/chef @halcyonCorsair @bhouse 

### References
 - Jira link: https://zendesk.atlassian.net/browse/OP-5530

### Risks
- AWS instances do not provision cleanly