Use 201 instead of 200 for action create of flavor-manage v3

All of v3 create action should return 201. Fix this for flavor-manage v3

Closes-bug: 1252162
DocImpact

Change-Id: I4fc698abdf89c93cb6ea0990ae43960f8c651d95
Merge "Use 201 instead of 200 for action create of flavor-manage v3"