Remove unwanted capability code per API council feedback.

The addition of hasUnwantedCapability was late in the release
cycle and does not simplify the API enough to be worth it. The
recommendation is, in a future release, to do something more
complete: not just add something like addUnwantedCapability, but
also deprecate all the NET_CAPABILITY_NOT_xxx constants and add
opposite NET_CAPABILITY_xxx constants for use with it.

Fix: 77601789
Test: builds, boots
Test: atest android.net.cts.NetworkRequestTest
Test: atest android.net.cts.ConnectivityManagerTest
Change-Id: Ib98fb01da4a4a0bae464787b589ad88f45002eb8