Add some hidden APIs back to NetworkTemplate

Since there's a bug about apps still call hidden
APIs, it's likely some developers might build apps
against hidden API.
To be safe, add these methods back to avoid apps
crash. These methods are still in
hiddenapi-max-target-o-low-priority.txt, so they
should not be removed without considering hidden
API usage. Removing hidden API in general isn't
forbidden, but the ones listed in hiddenapi usage
need extra care.

Bug: 269178029
Test: 1. atest CtsNetTestCases:android.net.netstats.NetworkTemplateTest
      2. CTS-13_R3
Change-Id: I485369274ccacd314230e3d267df665d8083bf97
1 file changed