Include both eth%d and usb%d ethernet interfaces on U+

Ethernet interface naming is not consistent on Linux. While some USB
ethernet dongles show up as eth0, others might show up as usb0.

This CL changes config_ethernet_iface_regex to "*" which stands for "use
Android version specific default". The default will include both usb\d+
and eth%d named interfaces on Android U+. Android T will continue to
only include eth%d interfaces (note that the "+" is a new addition which
is highly unlikely to have any actual effect, but is more technically
correct).

Bug: 304335605
Test: TH
Change-Id: I823be8ee390cb2b6dd41b537c72ed76f5aa9e0ea