Backport #17598 Backport #17606 Backport #17608 Backport #17609 - Since https://gitea.com/gitea/test-env/pulls/10 the golangci-lint has been upgraded and is erroring about new warnings in the code, this PR fixes those warnings.
* move database settings from models to setting * update docs * fix checkout pr * fix tests * fix lint * remove unsupported tidb options * correct wrong variable name * remove tidb totally