New isSubscriptionVisibleFlow

Use this instead of mSubscriptionInfoEntity, so MobileNetworkSettings
not closed unexpectedly.

Bug: 358238959
Flag: EXEMPT bug fix
Test: force stop settings & settings search - mobile settings
Test: adb shell am start -a android.settings.NETWORK_OPERATOR_SETTINGS
Change-Id: I34286da808600d8b9faa0da85a59665707ecfde3