Updated the settings for Tempest configuration

See the ticket [1] as the reason of the changes.

List of the main changes:

* Ability to set the CUSTOM_PUBLIC_NET_NAME - floating network
  in the offline and online methods of execution.
* The cvp.* flavors and images are not passed in tempest config.
* tempest_custom.yaml.clean file has reduced number of options
  (the old and irrelevant are removed).

[1] https://mirantis.jira.com/browse/PRODX-39383

Related-PROD: PROD-37187
Change-Id: I31e8c8e4b3d8eda706cbba46b4435d31f8f8eb4e
(cherry picked from commit ff980e1006dcfabc9622d0db7a6a0098f6ca03e4)
(cherry picked from commit 6b252d70db64ef5b981c18bc706fce712f1ce748)
5 files changed