Use get_my_ipv4 from oslo.utils

Remove _get_my_ip from ironic and replace it's usages
by usages of get_my_ipv4 from netutils, because this methods
implements the same functionality.

Change-Id: I85b75f26051170c0d306ef38b517cc1657e47a99
Merge "Use get_my_ipv4 from oslo.utils"