Fix assessment code not loading on initial assessment load

[sayomaki]

Description

The assessment template code and autograder test cases do not load on first entering the assessment (affects all missions, paths and quests). It appears that this is due to a regression that happened in 0d9d5dc in the leaderboard PR while implementing code loading when navigating to the assessment from the contest leaderboard (which is not in use at the moment).

Resolves #3300 and #3301.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Code quality improvements

How to test

Upon adding a new assessment and entering it the first time, programming question templates and test cases should show up right away.

Checklist

• I have tested this code
• I have updated the documentation

[coveralls]

Pull Request Test Coverage Report for Build 16942851937

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.002%) to 43.452%

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Totals
Change from base Build 16931123815:	-0.002%
Covered Lines:	20626
Relevant Lines:	49673

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💛 - Coveralls

[RichDom2185]

LGTM, didn't test, thanks!