### What changes were proposed in this pull request?
As title.
### Why are the changes needed?
To satisfy ASF policy.
```
An error occurred while processing the github feature in .asf.yaml:
GitHub discussions can only be enabled if a mailing list target exists for it.
---
With regards, ASF Infra.
For further information, please see the .asf.yaml documentation at:
https://github.com/apache/infrastructure-asfyaml/blob/main/README.md
```
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
This can be manually tested after merging to main.
Closes#3195 from pan3793/CELEBORN-1956.
Authored-by: Cheng Pan <chengpan@apache.org>
Signed-off-by: Cheng Pan <chengpan@apache.org>
