Fix 'New quiz' button is visible in the print report

[AllanOXDi]

Summary

This PR fixes the 'New quiz' / New lesson button being displayed in the 'Print preview.

Before

After

References

closes #12715

Reviewer guidance

1. Import the QA channel (nakav-mafak) and create quizzes assigned to learners
2. Complete some of the quizzes and go to Coach > Plan
3. Click the 'Print report' icon

[github-actions]

Build Artifacts

Asset type	Download link
PEX file	kolibri-0.18.0a0.dev0_git.163.g2f85216a.pex
Windows Installer (EXE)	kolibri-0.18.0a0.dev0+git.163.g2f85216a-windows-setup-unsigned.exe
Debian Package	kolibri_0.18.0a0.dev0+git.163.g2f85216a-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.18.0a0.dev0+git.163.g2f85216a.dmg
Android Package (APK)	kolibri-0.18.0a0.dev0+git.163.g2f85216a-0.1.4-debug.apk
Raspberry Pi Image	kolibri-pi-image-0.18.0a0.dev0+git.163.g2f85216a.zip
TAR file	kolibri-0.18.0a0.dev0+git.163.g2f85216a.tar.gz
WHL file	kolibri-0.18.0a0.dev0+git.163.g2f85216a-py2.py3-none-any.whl

[marcellamaki]

Hi @AllanOXDi - thanks for working on this. The solution you came up with is creative and does seem to fix the problem. For more simplicity, I think you could take your same idea but make use of some of the existing print functionality. Using @media print may be the most straightforward option, but if there are scenarios where this doesn't work, you could also look into the beforeprint and afterprint - there are some examples in the documentation. (This is actually a very similar idea to what you are already doing, actually, just a bit more specific - the benefit of which is that there is an exact event, rather than relying on guessing a number of ms for a timeout.)

Why don't you give these alternatives a try, see what you think, and let me know if you have any questions?