Add Tethering's UID to the legacy type NetworkCapabilities

This is needed because satisfiedByNC() compares UIDs by default now, and
the NCs we receive in callbacks have Tethering's UID patched in.

Bug: 72498421
Test: as follows
    - built
    - flashed
    - booted
    - runtest frameworks-net passes, module library loading failures:
Caused by: java.lang.UnsatisfiedLinkError: dlopen failed: library "libdexfile.so" not found
    - manually starting tethering works fine

Change-Id: I31f6516e2c1539809f8d052333fd2a616158cb92