GLQL table: Fix inclusion of table in description field

What does this MR do and why?

Fix inclusion of table in description field of a GLQL table view (edge case)

Fixes the rendering of sub tables in the description field in a scrollable table.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Enable GLQL echo "Feature.enable(:glql_integration)" | rails c
2. Use below snippet and add a darkmode screenshot to one of the listed issuable descriptions
3. Check the GLQL rendering

```glql
display: table
fields: state, title, description, assignee, labels("*"), labels("Bronco"), created, updated
query: opened = true
limit: 50
```

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Related to #512691 (closed), !183709 (merged)