KAFKA-20611: Stitch share group DLQ manager with the main code.

[smjn]

• Add ShareGroupDLQManager instance creation code in BrokerServer and
  pass along the instance to SharePartitionManager to be handed over to
  SharePartition.

NOTE: Merge after #22368 Reviewers:
Apoorv Mittal apoorvmittal10@gmail.com

Reviewers: Apoorv Mittal apoorvmittal10@gmail.com, Andrew Schofield
aschofield@confluent.io

[apoorvmittal10]

Overall looks good, 1 question though: the ShareGroupDLQManager is instatiated regardless of whether DLQ is enabled or not, as supplier is provided, hence do you think we can delay instatiation of ShareGroupDLQManager only when the share version is correctly toggled?

[apoorvmittal10]

I have added same in https://github.com/apache/kafka/pull/22407/changes#diff-1caaa9743f4aa4a5d156f2b3cc72b86079f5c17b944d5dfdda2d0d39e7f14816R44. So either of those should be required.

[smjn]

Overall looks good, 1 question though: the ShareGroupDLQManager is instatiated regardless of whether DLQ is enabled or not, as supplier is provided, hence do you think we can delay instatiation of ShareGroupDLQManager only when the share version is correctly toggled?

Hi, share.version=2 should be defaulted in the next release so above change will be transient as DLQ manager will always be needed