Fix the sample and unittest params of v3 scheduler-hints

The API samples of scheduler-hints contains "hypervisor" and "near"
attributes, but the attributes do not exist in the scheduler-hints
parameter of "create a server" API. This patch changes them to the
existing "same_host" attribute.
This patch also changes the attributes of some unit tests of the v3
scheduler-hints by the same attribute.

This nonexistent attributes are found during bp/nova-api-validation-fw
works. The implementation needs this change because it will deny the
unexpected attributes, which are not defined with API schema, in API
parameters.

DocImpact
Closes-Bug: #1278279

Change-Id: I8542f44b325ba909fdff8b569146c0015b150291
Merge "Fix the sample and unittest params of v3 scheduler-hints"