Enable more revive linter rules (#30608)

Noteable additions:

- `redefines-builtin-id` forbid variable names that shadow go builtins
- `empty-lines` remove unnecessary empty lines that `gofumpt` does not
remove for some reason
- `superfluous-else` eliminate more superfluous `else` branches

Rules are also sorted alphabetically and I cleaned up various parts of
`.golangci.yml`.

routers/api/v1/repo/mirror.go

@@ -180,7 +180,6 @@ func ListPushMirrors(ctx *context.APIContext) {
 		if err == nil {
 			responsePushMirrors = append(responsePushMirrors, m)
 		}
-
 	}
 	ctx.SetLinkHeader(len(responsePushMirrors), utils.GetListOptions(ctx).PageSize)
 	ctx.SetTotalCountHeader(count)