Tests: increase flaky test coverage for course model

[pretendWhale]

Motivation and Context

Due to non-deterministic ordering, coveralls reports that some lines are not covered. This PR aims to fix that by sorting the order of expected results rather than using if statements to concatenate them.

Your Changes

Description:
Updated course_spec.rb tests that coveralls was reporting as not tested to remove if statements.

Type of change (select all that apply):

• Test update (change that modifies or updates tests only)

Testing

Ran the new tests.

Questions and Comments (if applicable)

Checklist

• I have performed a self-review of my own code.
• I have verified that the pre-commit.ci checks have passed.
• I have verified that the CI tests have passed.
• I have reviewed the test coverage changes reported on Coveralls.

Pull request to make documentation changes (if applicable)

[coveralls]

Pull Request Test Coverage Report for Build 5513803615

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.007%) to 91.695%

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Totals
Change from base Build 5495942098:	0.007%
Covered Lines:	37132
Relevant Lines:	39960

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💛 - Coveralls

[david-yz-liu]

Thanks @pretendWhale!