As part of config refactoring process, it makes sense to
remove Debug field of AirshipCTLSettings and use log module
method as source of truth about current log level.
Change-Id: I42e3a9fd3b4e2778c71278f98a0d168421dfd2fb
Signed-off-by: Ruslan Aliev <raliev@mirantis.com>
Relates-To: #327