BC-8887 Remove all code regarding nexboard

[dyedwiper]

Description

Links to Tickets or other pull requests

https://ticketsystem.dbildungscloud.de/browse/BC-8887

Changes

Data Security

Deployment

New Repos, NPM packages or vendor scripts

Screenshots of UI changes

Approval for review

• 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.
• DEV: Every new component is implemented having accessibility in mind (e.g. aria-label, role property)

Notice: Please remove the WIP label if the PR is ready to review, otherwise nobody will review it.

[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