[ZOOKEEPER-3846] Add a couple TLS related metrics

• Type: Sub-task
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.6.2
• Component/s: metric system
• Assignee: Jie Huang
• Reporter: Jie Huang
• Created: 22/May/20 17:26
• Updated: 10/Sep/20 10:43
• Resolved: 28/May/20 03:47

Description

Adding those metrics:

• UNSUCCESSFUL_HANDSHAKE: number of unsuccessful TLS handshakes 
• INSECURE_ADMIN: number of insecure connections to admin port