Fix testGetConfigByComponentForSubId

Add null check for config bundle. Also remove size check for the bundle
since it can change frequently and cannot be enforced during compile
time. Instead test if the correct configs for the component are in the
config bundle.

Bug: 158222711
Test: atest CarrierConfigManagerTest

Change-Id: If29bdec4199d4ce1297f88ec7fb2f5c860d9e1b3