Split one test into two in MarkupTextTest

[Rian-Ismael]

Improves the readability of the test. Splitting assertions into separate tests improves clarity and ensures each test verifies a single scenario or state. This enhances readability, maintainability, and debugging efficiency.

Testing done

Modified automated tests pass with local testing

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Proposed upgrade guidelines

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1. There is automated testing or an explanation as to why this change has no tests.

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2. Conversations in the pull request are over, or it is explicit that a reviewer is not blocking the change.
3. Changelog entries in the pull request title and/or Proposed changelog entries are accurate, human-readable, and in the imperative mood.
4. Proper changelog labels are set so that the changelog can be generated automatically.
5. If the change needs additional upgrade steps from users, the upgrade-guide-needed label is set and there is a Proposed upgrade guidelines section in the pull request title (see example).
6. If it would make sense to backport the change to LTS, a Jira issue must exist, be a Bug or Improvement, and be labeled as lts-candidate to be considered (see query).

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