Reduce usage of db.DefaultContext (#27073)

Part of #27065

This reduces the usage of `db.DefaultContext`. I think I've got enough
files for the first PR. When this is merged, I will continue working on
this.

Considering how many files this PR affect, I hope it won't take to long
to merge, so I don't end up in the merge conflict hell.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/api/v1/org/org.go

@@ -203,7 +203,7 @@ func GetAll(ctx *context.APIContext) {
 
 	listOptions := utils.GetListOptions(ctx)
 
-	publicOrgs, maxResults, err := user_model.SearchUsers(&user_model.SearchUserOptions{
+	publicOrgs, maxResults, err := user_model.SearchUsers(ctx, &user_model.SearchUserOptions{
 		Actor:       ctx.Doer,
 		ListOptions: listOptions,
 		Type:        user_model.UserTypeOrganization,