[KAFKA-9599] create unique sensor to record group rebalance

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.0
• Fix Version/s: 2.5.0, 2.4.1
• Assignee: Chia-Ping Tsai
• Reporter: Chia-Ping Tsai
• Created: 24/Feb/20 09:30
• Updated: 24/Feb/20 19:40
• Resolved: 24/Feb/20 19:40

Description

  val offsetDeletionSensor = metrics.sensor("OffsetDeletions")

  ...

  val groupCompletedRebalanceSensor = metrics.sensor("OffsetDeletions")

the "offset deletion" and "group rebalance" should not be recorded by the same sensor since they are totally different.

the code is introduced by KAFKA-8730