Migrate prow kubernetes type jobs which run on cluster `gcp-prow-ksyun` to `default` cluster

[wuhuizuo]

prow job default cluster is default, so when we migrate them, we can just delete the cluster field in prow job. And some additional changes we need to make:

1. when the job use go build or go mod cache env vars and volume and volume mounts, please delete it.
2. when use images from hub.pingcap.net, your should add a task item in the pull request description and assign the pr to @wuhuizuo and add label "help wanted" to request help.