Remove non-locking accounts from the config guide

Before Tempest had three different methods of providing authentication,
dynamic credentials, locking test accounts and non-locking test
accounts, currently only the first two are supported. This commit
updates a section on the configuration guide where it still mentions
three methods.

Change-Id: I532aff27a803b9fd34e994153f4183de48d91d00
Closes-Bug: 1600319
1 file changed