[Bug] Paimon Table produce more reduce task for same data volume

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/incubator-paimon/issues) and found nothing similar.

### Paimon version

0.4

### Compute Engine

hive

### Minimal reproduce step

Compare the paimon table and hive table with the same statement and data amount using the hive client:
painmon table:


hive table：


### What doesn't meet your expectations?

read paimon table should have lower reducer number.

### Anything else?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Start by reproducing the comparison from the issue with Paimon 0.4 and the Hive client, using identical statements and data volumes for Paimon and Hive tables. Investigate the reducer-task planning path and compare the resulting task counts. Done means the Paimon table no longer produces more reducers than the equivalent Hive table, with a regression test if the relevant test location is identified.

Written by the indexing model from the issue text.