No show DisableSimFooterPreference when sub not found

DisableSimFooterPreferenceController.getAvailabilityStatus() used to
return AVAILABLE when the subscription is not found in selectable
subscription info list.

Return CONDITIONALLY_UNAVAILABLE in this case to fix.

Bug: 336232487
Test: manual - on Mobile Settings
Change-Id: I88642fc9853ce6603a78dfdc0e5fed1da1553adc