When user's job config is too large, OpenPAI job will be in Waiting or Stopping forever

[hzy46]

1. To reproduce this issue, use a job config with 1000+ lines. You can set up a lot of taskroles to achieve this.

2. The job will be in Waiting status. POST request to K8S api server reports Resource Exhausted

3. PATCH will fail because of entity too large, and it doesn't report a 404 error.

4. If user tries to stop this job, it will be in Stopping status forever.

5. It may be related to make DBController tolerant to wrong framework request #4889

[yqwang-ms]

Except #4889, for this specific case, we should also limit the job config size to a reasonable value.