Fix Analytics dashboards description `Show more` toggle button

What does this MR do and why?

Fixes a bug that was causing the Show more button to render on analytics dashboard descriptions, even when it wasn't required.

References

• #464806 (comment 1934063624)
• gitlab-ui#2552 (moved)

MR acceptance checklist

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Screenshots or screen recordings

Before	After

How to set up and validate locally

• Navigate to the analytics dashboard list for any group (ex. http://gdk.test:3000/groups/flightjs/-/analytics/dashboards/)
• Validate that the Show more button is not rendered for the Value streams dashboard.
• Modify the Value streams dashboard YAML to try different descriptions and ensure the Show more button only appears when necessary

Related to #464806 (closed)