allow rbac tests to run

[torcolvin]

I'm not actually sure what feature is only supported in 7.1 in this test - I think it's user creation, but if it's not, let me know how to change this test.

There were a few changes to make to this test with database and keyspace which are expected.

Unexpected was that /_stats and /_expvar/ are granted to syncGatewayConfigurator

Pre-review checklist

• Removed debug logging (fmt.Print, log.Print, ...)
• Logging sensitive data? Make sure it's tagged (e.g. base.UD(docID), base.MD(dbName))
• Updated relevant information in the API specifications (such as endpoint descriptions, schemas, ...) in docs/api

Integration Tests

• GSI=true,xattrs=true https://jenkins.sgwdev.com/job/SyncGateway-Integration/1760/

[adamcfraser]

The majority of the RBAC permissions being used in that test (sync_gateway_dev_ops, etc - everything except mobile_sync_gateway) didn't exist until server 7.1. So instead of supportsSettingRBAC, the cluster capability is more like 'includes mobile permissions'.