Fix "force private" logic (#31012)

When creating a repo, the "FORCE_PRIVATE" config option should be
respected, `readonly` doesn't work for checkbox, so it should use
`disabled` attribute.

routers/api/v1/repo/repo.go

@@ -252,7 +252,7 @@ func CreateUserRepo(ctx *context.APIContext, owner *user_model.User, opt api.Cre
 		Gitignores:       opt.Gitignores,
 		License:          opt.License,
 		Readme:           opt.Readme,
-		IsPrivate:        opt.Private,
+		IsPrivate:        opt.Private || setting.Repository.ForcePrivate,
 		AutoInit:         opt.AutoInit,
 		DefaultBranch:    opt.DefaultBranch,
 		TrustModel:       repo_model.ToTrustModel(opt.TrustModel),
@@ -364,7 +364,7 @@ func Generate(ctx *context.APIContext) {
 		Name:            form.Name,
 		DefaultBranch:   form.DefaultBranch,
 		Description:     form.Description,
-		Private:         form.Private,
+		Private:         form.Private || setting.Repository.ForcePrivate,
 		GitContent:      form.GitContent,
 		Topics:          form.Topics,
 		GitHooks:        form.GitHooks,