Annotate NetworkInformationShimImpl for api 31 with @RequiresApi(S)

An update to lint finds a new error:
packages/modules/NetworkStack/apishim/31/com/android/networkstack/apishim/api31/NetworkInformationShimImpl.java:35: Error: Extending NetworkInformationShimImpl requires API level 30 (current min is 29): NetworkInformationShimImpl [NewApi]
        extends com.android.networkstack.apishim.api30.NetworkInformationShimImpl {
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Annotate api31.NetworkInformationShimImpl with @RequiresApi(S).

Also remove the unnecesary useApiAboveR and useApiAboveQ.

Test: m lint-check
Change-Id: Ib86978557972e6ee8d0288770e7cb8fc758a6219
Merged-In: Ib86978557972e6ee8d0288770e7cb8fc758a6219