[fuel] Explicitly blacklist incompatible labs

[fuel] Explicitly blacklist incompatible labs

Previously, we used to silently refuse to construct 'pod_config'
for PODs missing mandatory PDF/IDF configuration; and instead
generated an empty output YAML.

Retire safety checks in Fuel IA and explicitly blacklist Fuel via
new 'idf.installer' where appropiate.

The following PODs do not yet support Fuel due to missing 'idf.fuel':
- ericsson-pod2
- huawei-pod1
- intel-pod18
- nokia-pod1
- zte-pod2
- zte-pod3

Change-Id: Ief62d62f99a79187303e3f15b83030289e5efdcb
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>