ERROR: deletes on append-only tables are not supported in serializable transactions

### What happens?

ERROR: deletes on append-only tables are not supported in serializable transactions

### To Reproduce

I am computing in DuckDB and then writing the results back to Greenplum. Before writing, I need to delete existing data, but I tried two methods:
```
delete from gp.dm.fct_sale_stockorg_kpi
where day_date > ('2024-07-04'::timestamp - '40 day'::interval) and day_date <= ('2024-07-04'::timestamp)
```
method2:
```
call postgres_execute('gp',$gp$
delete from dm.fct_sale_stockorg_kpi
where day_date > ('2024-07-04'::timestamp - '40 day'::interval) and day_date <= ('2024-07-04'::timestamp)
$gp$)
```
the first method is very slow,
and the second method gives an error as described in the title.
why?

### OS:

centos7

### PostgreSQL Version:

gp7.1(pg12.12)

### DuckDB Version:

1.0.0

### DuckDB Client:

python3.9

### Full Name:

wang cz

### Affiliation:

Linezone

### Have you tried this on the latest `main` branch?

- [X] I agree

### Have you tried the steps to reproduce? Do they include all relevant data and configuration? Does the issue you report still appear there?

- [X] I agree