[ECM] Legacy code: treat DEFAULT as ALLOWED

This modifies pre-flag behavior so that MODE_DEFAULT (of
OP_ACCESS_RESTRICTED_SETTINGS) is treated the
same as MODE_ALLOWED.

The reason is that we've change the default op mode (of
OP_ACCESS_RESTRICTED_SETTINGS) to MODE_DEFAULT. Since legacy code
doesn't understand what MODE_DEFAULT means, we need to mitigate the
impact of reverted flags.

Bug: 329488185
Test: atest SpaPrivilegedLibTests
Test: atest com.android.settings.applications.specialaccess.notificationaccess
Test: atest com.android.settings.datausage
Test: atest PremiumSmsAccessTest
Test: atest RestrictedPreferenceHelperTest
Test: atest CtsPermissionUiTestCases:android.permissionui.cts.EnhancedConfirmationManagerTest
Change-Id: Ibf14e41d2e6eda025788a34ea5a29a11321ab696