NEXUS-6219: Duplicate processing of reposes

When bulk operation happened (as task om "all" repositories)
or user right-clicked on UI over some group that contained
groups-of-groups (or just same repo was resolved multiple times)
the some repositories were processed multiple times.

Affected actions:

Hosted repositories:
* expireCaches
* expireNotFoundCaches
* evictUnusedItems
* recreateAttributes

Proxy repositories:
* expireProxyCaches

Maven repositories
* recreateMavenMetadata

Issue
https://issues.sonatype.org/browse/NEXUS-6219

CI
TBD