[Compatibility] rand() rejects an integer seed argument (RAND(N) not supported)

## Summary
`rand()` rejects an integer seed, while MySQL supports `RAND(N)` for reproducible sequences.

## Environment
- **Reported on:** MatrixOne Cloud free tier, `8.0.30-MatrixOne-v3.0.11`
- **Retested on:** local Docker `matrixorigin/matrixone` **main branch** build, Git commit `0bfda60` (built 2026-05-30), version string `8.0.30-MatrixOne-v`

## Test case
```sql
SELECT rand(123);
```

## Actual result
```
ERROR 20203 (HY000): invalid argument function rand, bad value [BIGINT]
```

## Expected
`RAND(N)` with an integer seed should be accepted (MySQL compatibility).

## Version status
- v3.0.11 (Cloud): reproduces
- main / 4.0-dev (commit 0bfda60): reproduces