Copy updates to-do list empty state

Follow up/address Lorena's comments from !165211 (comment 2097101438)

👋 @leipert @ameliabauerly I have two suggestions that maybe could be addressed in a follow-up MR:

• No pending todos: The title Give yourself a pat on the back! doesn't say explicitly that there are no open to-dos left, like the other title options. I think we should specify this in the text, for example: Give yourself a pat on the back for completing all your to-do items!
• No filtered todos: We should remove Sorry and add a description below the title: To widen your search, change or remove filters above.