Reset GeoIP cookie upon encountering invalid country code

In EventLogging we were seeing lots of clients reporting a country
value of 'GeoIP='. These seem to stem from old, gone wrong GeoIP
assignments that are stil stored on the client. So we reset those
cookies instead of using obviously wrong values.

Bug: 66478
Change-Id: I1364ab4c56795275d483f04b5a1d4fb99e839a22