Invalid metrics names in zookeeper for topics with underscore in name

[druminski]

When topic has underscore char in name then its counters are kept in zookeeper under wrong path (underscores are escaped to dots). Hence, for this topic:

• counter values are not read properly so user sees 0 for published, delivered, discarded counters
• counted number of consumers assigned to subscription is always 1. Because of this calculated max-rate is too high