Invesigate and cleanup approval_required and review_submitted todo action types

After review of !90853 and following Slack discussion we noticed that we have (at least) two Todo action types where we are not sure if they are still needed today:

1. approval_required seems to not get created "since 2023".
2. review_submitted "was added with one of the ai features and then it was removed".

We want to investigate if these are still created today. If no, we have to decide if just want to mark them as deprecated, keeping old records in the db (which then requires the enum value to stay), or if we could actually fully delete data and type.