Remove deprecated nova_create_flavors.sh script

nova_create_flavors.sh has been deprecated for over a year (since 2013-05-07)

Removing the script, since it is not documented in any current READMEs
or on the Openstack wiki.

Change-Id: Ib6031c2518b8e6d43bb692e0f687a2e287ec494f
Partial-Bug: 1338066