The values are only read during startup so moving these to a boot
namespace. This will ensure that the values are committed to logs only
after a boot.
The boot namespace is already provisioned, but going forward the
string constants for the namespace do not need to be defined in the
DeviceConfig module.
Test: atest ConnectivityCoverageTests:\
android.net.connectivity.com.android.server.CSNetworkActivityTest
Test: Manually using shell commands. E.g.:
adb shell device_config put tethering_boot \
cellular_data_inactivity_timeout 4
Bug: 377759682
Change-Id: Icd4bd3da288e5dfde620d779bd0708319da90be9
392336b50d