After TrueCloudLab/frostfs-contract#117
we allow checking for root domain availability directly.
Before this commit, NNSRootRegistered() has always returned true, so the
actual root registration happened as a side-effect of the following
code, because NNS registers all parent domains, if they are missing.
Change-Id: Icf98f130e77d31b4af7b69697989183c1c8f6a56
Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>