Don't dynamically create provider types in the global env

Only support this in user environments.
Note: this is only when you have the following in your template
resources:
  thingy:
    type: http://example.com/foo.template

Doing this will avoid tenant-specific provider template URLs being
shown globally in the resource-type listing.

Co-Authored-By: Angus Salkeld <angus.salkeld@rackspace.com>
Closes-Bug: #1311223
Change-Id: Ifa18108afacbda390b19b46a8f41bc4f018e95d6
(cherry picked from commit a02ff20509171346d2a1d2a9df7c81aada134c52)