Keep initial override configuration from display settings

During register configuration change listener, the override
configuration will update from the container to listener.
When linking ActivityDisplay to an existing DisplayConent,
the empty configuration will replace the applied override
configuration which should be kept.

Bug: 119919497
Test: Enable freeform, desktop mode and simulate secondary displays
      in developer options. Launch an resizable activity in that
      display and check if the activity is freeform style.

Change-Id: Ic7d38dc1b9a551b78f41de43c38fac2caeab33d4