[Java] Use new implementation to concat vectors values in batch #23807
Description
Per discussion #5945 (comment).
In ARROW-7284, we write a simple method to concat vectors. However, ARROW-7073 is about to concat vector values efficiently, after this PR merged, we should use this new implementation in ArrowReader.
Reporter: Ji Liu / @tianchen92
Assignee: Ji Liu / @tianchen92
PRs and other links:
Note: This issue was originally created as ARROW-7546. Please see the migration documentation for further details.