Trip addition overhaul

[xsaschako]

Motivation / Current Behaviour

Trips are added one by one
weeknd trips possible

Enhancement description

• Just add all trips directly. Then sort. It's a huge performance gain (in its current form adding many trips are not even feasible to add).
• We'll delete weekend trips for now. The'll be reintroduced when they come around again in a better implementation of trips. (reduce error proneness).

Additional context

No response

Checklist

• Attached labels, especially loc:: or model:: labels.
• Linked to project