Populate OemManagedBytesTransfer without metered

Slice OemManagedBytesTransfer by uid + fg/bg status, and not by
meteredness. The atom does not have a metered or tag field, so there is
no reason to slice by metered or tag.

Populate the transport field of OemManagedBytesTransfer with
NetworkCapabilities.TRANSPORT_<type> instead of using NetworkTemplate
match rules.

Bug: 201979463
Test: Verify output of statsd_testdrive 10100 and adb shell dumpsys
netstats --uid are correct and consistent

Change-Id: I9178893e36eca1bae8df0063ee35680f7af20944