…single snapshot scenario (#58239)

### What problem does this PR solve?

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:
When a Paimon table has only 1 snapshot, users cannot perform
incremental queries. The validation logic in Doris has two issues:

1. It rejects queries where `startSnapshotId = endSnapshotId`:
```sql
SELECT * FROM tb_simple@incr('startSnapshotId'='1', 'endSnapshotId'='1');
-- Error: startSnapshotId must be less than endSnapshotId
```

2. It rejects queries where `startSnapshotId = 0` (which is needed to
query all data from a single snapshot):
```sql
SELECT * FROM tb_simple@incr('startSnapshotId'='0', 'endSnapshotId'='1');
-- Error: startSnapshotId must be greater than 0
```

This behavior is inconsistent with Spark Paimon, which:
- Allows `startSnapshotId = endSnapshotId` (returns empty result)
- Allows `startSnapshotId = 0` to query all data from the initial state
to the specified snapshot

## Solution

Align Doris incremental query behavior with Spark Paimon:

1. **Allow `startSnapshotId = 0`**: This enables querying all data from
a single snapshot by using `startSnapshotId=0, endSnapshotId=1`
2. **Allow `startSnapshotId = endSnapshotId`**: This matches Spark
Paimon behavior (returns empty result when querying the same snapshot)
3. **Update validation**: Allow `startSnapshotId >= 0` and
`endSnapshotId >= 0` (previously `> 0`)