[Bug] FlinkCdcMultiTableSink doesn't support flink batch mode

### Search before asking

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

### Paimon version

0.5

### Compute Engine

flink 1.17

### Minimal reproduce step

Run a paimon cdc with
- sync whole database
- combined
- flink execution mode is batch

### What doesn't meet your expectations?

After the flink batch job finished successfully, data is written but no new snapshots generated in paimon tables .

### Anything else?

_No response_

### Are you willing to submit a PR?

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

Start by locating FlinkCdcMultiTableSink and its handling of Flink 1.17 batch execution for combined, whole-database CDC synchronization. Reproduce the issue with the described setup and compare the resulting Paimon table state with streaming mode. Done means the batch job writes data and generates new snapshots in the affected Paimon tables.

Written by the indexing model from the issue text.