Creation of a single cluster and creation of multiple clusters will now
share an API endpoint (in the APIv2 case). More specifically, the
original single-cluster endpoint will accept a `count` parameter in the
request and the multiple-cluster endpoint has been removed.
We can make this kind of change because APIv2 is still experimental.
Also, when creating multiple clusters, the response will now contain
all details about the clusters; previously, the response simply gave
cluster IDs.
Change-Id: I90faf4956a8ea4b4ae31a29382732771fdfddecb
Story: 2002099
Task: 19777
f96709a59e