[Partial Screen Sharing] Fix default option when single app is disabled

When single app sharing is disabled by the host app, we were disabling
the option in the popup, but still showing it as the default option.

Fixes: 310738757
Test: Manual
Test: MediaProjectionPermissionTest
Flag: LEGACY enable_record_task_content ENABLED
Change-Id: I49bd8d8555fecbaedea5e5eb71675c32a0a2bb0b