Track local network ifindices in sInterfaceToTable as well.

RouteController tracks in the sInterfaceToTable map the the
interface indices of every interface used in physical and virtual
networks. This ensures that when an interface is removed from a
network (by passing in the interface name), the rules (which
specify interface indices) are correctly deleted even if the
interface has been deleted or has been deleted and re-added with
a new interface index.

Currently this does not happen for interfaces added to the local
network. That means that when those interfaces are deleted, the
rules might not be deleted. It also results in spurious messages
logged by NetworkController such as:

03-24 00:38:47.553 16612 16635 E Netd    : getIfIndex: cannot find interface testtap1
03-24 00:38:47.553 16612 16635 E Netd    : inconceivable! added interface testtap1 with no index

Note that since P this map is read by RouteController::getIfIndex
and used by code that assumes this will always return an
interface index. In the case of an interface in the local
network, this is not possible because the map stores mappings
between ifindex and routing table. In the case of the local
network, the routing table is always ROUTE_TABLE_LOCAL_NETWORK,
so there is no way to get the interface index. Fix these callers
so they do not attempt do to this.

Bug: 150644681
Test: TetheringIntegrationTests:EthernetTetheringTest
Original-Change: https://android-review.googlesource.com/1277438
Merged-In: I8042e5b91bcb3175d9ad540526df396a139976f0
Change-Id: I8042e5b91bcb3175d9ad540526df396a139976f0