Adapter test fix: Recreate config after factory reset

Obfuscate test expect a config to be present, but gd will delete the
config if there is no 'Adapter' section.
Enabling bt at the end of the test is the easier way to create this
config

Fix: 267528843
Test: atest BluetoothInstrumentationTests:com.android.bluetooth.btservice
Change-Id: I34f570fa1e18b8674e090c7809e68dab6eafa312