fix: duplicate courses and batches in created lists

[zaveshaa]

Fixes #2476.

get_created_courses() joins Course Instructor with LMS Course, so each course is returned once per instructor row. A course with 3 instructors shows up 3 times on the moderator home page and fills the whole limit(3), hiding other courses.

The fix adds .distinct() to the course query. While testing the same pattern I noticed get_created_batches() has the same issue when the current user is one of several instructors on a batch, so it got the same one-line fix.

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains within the eligible follow-up scope.

_{Reviews (3): Last reviewed commit: "Merge develop into fix-created-courses-d..." | Re-trigger Greptile}

[raizasafeel]

As per our commit guidelines we need you to follow conventional commit so please edit the message as fix(subject): message or fix: message

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.47%. Comparing base (47fd185) to head (aa3325b).
⚠️ Report is 7 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2686   +/-   ##
========================================
  Coverage    76.47%   76.47%           
========================================
  Files          186      186           
  Lines        11700    11700           
========================================
  Hits          8947     8947           
  Misses        2753     2753           

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[zaveshaa]

Done — the commit message is now fix: Remove duplicate courses and batches in the created lists, following the conventional commit format. I also merged the latest develop in so the branch is up to date.