fix: #1477: use correct student login URL in level editor JS

[benbacardi]

Description

Use the correct student login URL in the level editor popup.

How Has This Been Tested?

Tested locally in the browser.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have linked this PR to a ZenHub Issue.

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3c26016) 91.79% compared to head (2164b26) 91.69%.
Report is 2 commits behind head on master.

❗ Current head 2164b26 differs from pull request most recent head b92d19d. Consider uploading reports for the commit b92d19d to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1514      +/-   ##
==========================================
- Coverage   91.79%   91.69%   -0.11%     
==========================================
  Files         110      110              
  Lines        5875     5864      -11     
==========================================
- Hits         5393     5377      -16     
- Misses        482      487       +5     

see 6 files with indirect coverage changes

[faucomte97]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @benbacardi)