Fix up os-collect-config.conf on the seed

Move the creation of os-collect-config.conf on the seed to
11-seed-stack-heat-metadata so it happens after 10-os-collect-config
(and doesn't get overwriten).
Also change case of the default section to DEFAULT, oslo.config requires
it to be uppercase.

Change-Id: I6b75d448384e1647f8414765c8122460e6c28e60
Merge "Fix up os-collect-config.conf on the seed"