[improve][broker] Reduce memory occupation of InMemoryRedeliveryTracker.

[thetumbled]

Motivation

Reduce memory occupation of the InMemoryRedeliveryTracker.

Modifications

Use Long2ObjectMap<Long2IntMap> to replace ConcurrentLongLongPairHashMap.

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: thetumbled#66