fix: make creating of schools work again for superheros

[hoeppner-dataport]

Description

Make creating of new schools work again for superheros.

• it is possible now to create schools in one step without the workaround superheros were used to
• gradually creating a school (enter name, save, edit, ...) is also possible
• feature-checkboxes can be checked in the first step, too
• feature-checkboxes for Messengers were removed (are outdated)

Links to Tickets or other pull requests

BC-8182
hpi-schul-cloud/superhero-dashboard#273

Approval for review

• DEV: If api was changed - generate-client:server was executed in vue frontend and changes were tested and put in a PR with the same branch name.
• QA: In addition to review, the code has been manually tested (if manual testing is possible)
• All points were discussed with the ticket creator, support-team or product owner. The code upholds all quality guidelines from the PR-template.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud