fix: make learner name capitalized

[sundasnoreen12]

INF-2095

Description

This PR corrects the casing of usernames displayed in the Learners tab to ensure consistency with platform-wide formatting guidelines. Previously, usernames appeared with inconsistent capitalization, which could lead to a poor user experience and visual inconsistency.

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• If your update includes visual changes, have they been reviewed by a designer? Send them a link to the Sandbox, if applicable.
• Is there adequate test coverage for your changes?

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• Deploy the changes to prod after verifying on stage or ask @openedx/edx-infinity to do it.
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.11%. Comparing base (9e7b7ae) to head (e8aa758).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #800   +/-   ##
=======================================
  Coverage   94.11%   94.11%           
=======================================
  Files         166      166           
  Lines        3687     3687           
  Branches      997      993    -4     
=======================================
  Hits         3470     3470           
  Misses        202      202           
  Partials       15       15           

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