MINOR; Clean up LeaderAndIsrResponse construction in ReplicaManager#becomeLeaderOrFollower

[dajac]

This patch refactors the code, which constructs the LeaderAndIsrResponse in ReplicaManager#becomeLeaderOrFollower, to improve the readability and to remove unnecessary operations.

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[jolshan]

Thanks for the PR. This really cleans up the code. LGTM

[chia7712]

+1 if the following question is invalid :)

[dajac]

@chia7712 Thanks for the review. I just pushed a commit to address your comment. Could you take another look?

[chia7712]

+1 to this nice patch. nit: The topic name is a bit mysterious to me when reading so it would be nice to add some comments :)

[dajac]

@chia7712 I just pushed another small commit to fix/improve LeaderAndIsrRequestTest#testGetErrorResponse. It was not testing all the versions as claimed. I have also added assertions to verify the created response. Could you take a look?

[chia7712]

+1 again. one question unrelated to this PR is left :)

[dajac]

@chia7712 I just pushed a commit to address your comment. Could you take a look?

[chia7712]

LGTM