Update the MR template
- use comments instead of texts for instructions (avoiding ugly parantheses)
- remove "does this impact" because localization, dark/light mode should always be taken care of. same with guest-mode.
- remove screenshots section because if there should be any screenshots, they can be inserted in the summary
- remove "Developer Testing Completed" because it should always be completed. if it's not, the MR will be in draft
- remove "Ticket(s) / Related Merge Requests" because ticket should always be in the MR title and related MRs have their own section in gitlab