SKU type is undefined if no default cluster defined in virtualClusters

Organization Name:
enflame

Short summary about the issue/question:
SKU type is undefined if no default cluster defined in virtualClusters

Brief what process you are following:
modify virtualClusters settings.

How to reproduce it:
Rename the "default" cluster to something else in hivedscheduler.config.virtualClusters in services-configuration.yaml. And apply the change:

echo pai | /pai/paictl.py service stop -n rest-server hivedscheduler
echo pai | /pai/paictl.py config push -p /cluster-configuration/ -m service
echo pai | /pai/paictl.py service start -n hivedscheduler rest-server

Go to "Job submission" page in OpenPAI web UI. SKU type is undefined.

OpenPAI Environment:

• OpenPAI version: commit 8ae06ba6e84a5b4276abb8936d63179b9d88f432
• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release): ubuntu 16.04
• Kernel (e.g. uname -a): Linux registry 4.4.0-186-generic #216-Ubuntu SMP Wed Jul 1 05:34:05 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
• Hardware (e.g. core number, memory size, storage size, GPU type etc.):
• Others:

Anything else we need to know: