### What this PR does / why we need it?
Fix `ValueError: Unrecognized distributed executor backend tp. Supported
values are 'ray', 'mp' 'uni', 'external_launcher' or custom ExecutorBase
subclass.`
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Test on my local node
Signed-off-by: Yikun Jiang <yikunkero@gmail.com>