Fix getResourcesForRotation to avoid overriding the entire configuration

The configuration context created was overriding the entire
configuration, which is wrong: if anything in the base context changes
(e.g. display caracteristics), we want it to be reflected in the new
context and resources.

While this didn't result in any user visible issue right now (as this resource instance was never being cached), it could have (as we've seen in several other cases.

Bug: 437082130
Test: NONE - small bugfix, hard to test reliably
Flag: com.android.systemui.shared.status_bar_connected_displays
Change-Id: Iccb0e890955353d817ef396bea90a56be26bd026