Initialize settings only for default device during boot

Avoid invoking VirtualDeviceManager to get virtual device
id's during SettingsProvider#onCreate. Only initialize settings
for Context#DEVICE_ID_DEFAULT.

Test: atest SettingsProviderTest
Bug: 412634873
Flag: EXEMPT bugfix
Change-Id: Ibbc34eaad56d1bda02ed88300f04bb54c5893f6a