Disable Fold lock behavior setting by default

Flag protect Fold lock behavior setting behind a sysprop flag.
The setting will be disabled by default and can be
teamfooded by enabling sysprop flag with prop name
persist.fold_lock_setting_enabled.
Enable sysprop flag by running following command
* adb root && adb shell setprop persist.fold_lock_setting_enabled true

Flag: persist.fold_lock_setting_enabled
Bug: 298200843
Test: atest FoldSettingProviderTest FoldLockBehaviorPreferenceControllerTest
* Manually check if the setting accessible with sysprop flag true and
false.

Change-Id: Iaca4333b3e50383a621b5ae5f704410648ed205f