Changes

testenv: bridge: change default IPs 201 -> 1

During code review it was decided that we want to keep the 127.0.0.1
(and other 127.0.0.x) IPs in the configs, so one can start the testsuite
with osmo-ggsn directly on the host without using testenv scripts too,
with the same config.

The testenv script for osmo-ggsn will replace 127.0.0.x with 172.18.3.x
on the fly before the testsuite starts, so we can run osmo-ggsn
optionally in QEMU on 172.18.3.2, which will be bridged to the host.

172.18.3.1 will be used by the GGSN testsuite now, instead of
172.18.3.201 as previously planned, so change the default IP of the
bridge. The bridge is not used for another testsuite yet.

Add the 201 IPs as EXTRA_IPS for the non-QEMU case, as they are
configured as DNS IPs and tests need to be able to reach them.

Change-Id: Ied055e6e4d6214fd5247694e697a35a1e8ff1966