Add cypress tests for partial page load on vocab home page

[UnniKohonen]

Reasons for creating this PR

Adding cypress tests for partial page load on vocab home page

Link to relevant issue(s), if any

• Closes #

Description of the changes in this PR

• Add cypress test for partial page load

Known problems or uncertainties in this PR

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that show that the new code works, or tests are not relevant for this PR (e.g. only HTML/CSS changes)
• The PR doesn't reduce accessibility of the front-end code (e.g. tab focus, scaling to different resolutions, use of .sr-only class, color contrast)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[osma]

This code is old and difficult to salvage as so much around it has changed. But I implemented similar tests, partly inspired by these, in PR #1605. Closing this PR.