We propose adding the following new metrics, which will be present only in KRaft mode.

Name	Context	Type	Description
`kafka.controller:type=KafkaController,name=TimedOutBrokerHeartbeats`	Controller	Long	The number of broker heartbeats that timed out on this controller since the process was started. Note that only active controllers handle heartbeats, so only they will see increases in this metric.
`kafka.controller:type=KafkaController,name=EventQueueOperationsPerformed`	Controllers	Long	The total number of event queue operations that were performed. This includes deferred operations.
`kafka.controller:type=KafkaController,name=EventQueueOperationsTimedOut`	Controllers	Long	The total number of event queue operations that timed out before they could be performed.
`kafka.controller:type=KafkaController,name=NewActiveControllersCount`	Controller	Long	Counts the number of times this node has seen a new controller elected. A transition to the "no leader" state is not counted here. If the same controller as before becomes active, that still counts.
`kafka.server:type=MetadataLoader,name=CurrentMetadataVersion`	Broker and Controller	Integer	Outputs the current effective metadata version as an integer value.
`kafka.server:type=MetadataLoader,name=HandleLoadSnapshotCount`	Broker and Controller	Long	The total number of times we have loaded a KRaft snapshot since the process was started.

Rationale

TimedOutBrokerHeartbeats

...