Avoid RequestURITooLong exception in metadata agent

Length of API port query is proportional to number of networks
and may exceed URI limit. The solution is to query ports by
given ip address only and then filter them by network_id.

Closes bug 1348097

Change-Id: I2a87d6b215df380b24dd5ebb24947e8729f3f6fb
Merge "Avoid RequestURITooLong exception in metadata agent"