The send node of the load will consume too much sending memory when cluster is large

[trueeyu]

Enhancement

When the scale of the cluster is relatively large, the send node of the load will consume too much sending memory

[github-actions[bot]]

We have marked this issue as stale because it has been inactive for 6 months. If this issue is still relevant, removing the stale label or adding a comment will keep it active. Otherwise, we'll close it in 10 days to keep the issue queue tidy. Thank you for your contribution to StarRocks!