Fix lockscreen.rot_override precedence

Since config_enableLockScreenRotation was introduced, the override
only allowed forcing keyguard rotation *on*. Not *off* which can also
be useful depending on the device-under-test.

Bug: 355144756
Change-Id: Ide938ee9baff0155f4f742cafda5a14f613e8e96
Flag: EXEMPT adjusting a legacy flag