Logging improvements when NetworkCapabilities change

This patch improves the wtf() logging in updateCapabilities to
better distinguish between the cases of a changed specifiers, changed
transports, or changed capabilities. The case of NOT_METERED being added
or removed is ignored.

Bug: 63326103
Test: runtest frameworks-net, runtest frameworks-wifi
Change-Id: I05c6e78891e1eac658f1cf883223af520a9a4f8f