- group manifests from several CNFs into one
  common_manifests.yaml file
- add functionality in cleanup.cr to remove this file
- depends on PR in helm library:
  cnf-testsuite/helm#4
- common_manifest functionality: used common_manifest
  instead of templates
- remove methods related to templates
- update generated manifest: add namespace to each
  resource

Signed-off-by: barmull <barbora.muller@tietoevry.com>

Temporarily disable cnf_to_new_cluster tests as this process needs
to be redesigned to new installation format.
Also, adapt service_discovery to namespaced manifest generation.

Refs: #2153
Signed-off-by: Konstantin Yarovoy <konstantin.yarovoy@tietoevry.com>