Replace internal calls of create_{network, subnet, port}

Replace internal calls of create_{network, subnet, port}

When API controller calls method create_{network, subnet, port),
it made sure that the necessary default values for attrs are filled properly
according to attr mapping.

However, internal calls to these methods do not follow the convention,
when extension codes miss these values, exceptions will be thrown.

This patch introduces helper functions to fix up arguments and replaces
the direct callers of those methods.

Co-Authored-By: gong yong sheng <gong.yongsheng@99cloud.net>
Co-Authored-By: yalei wang <yalei.wang@intel.com>
Change-Id: Ibc6ff897a1a00665a403981a218100a698eb1c33
Closes-Bug: #1383546