Fix artifact import error '@ERROR: invalid uid root'
Fix artifact import error '@ERROR: invalid uid root'

Use 0:0 instead of root:root symbolic names in rsyncd which runs inside artifact.

Issue reproduces when artifact image does not have root line in the `/etc/passwd` file.

Refs https://github.com/werf/werf/issues/2762

flant/dapp,flant/dapp,flant/dapp