Remove Nova v3 version API schema

The commit Ia8e03aad49c524e5c3df110f0737eee3262b93e6 added a response
schema for Nova v3 version API. However the v3 API has been removed
but we forgot to remove it.
This patch removes it for the cleanup before adding the response
schema of Nova v2/v2.1 version API.

Change-Id: I5e96630fe9d4ae424df7064f4f759497c634f02c
1 file changed