Hide table sticky-header shadow when description is truncated

What does this MR do and why?

When a work item description contains a markdown table with sticky headers and is long enough to trigger the "Read more" truncation, the table's sticky-header scroll shadows bleed through the truncation overlay

References

• #622480 (closed)

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Enable the FF editor_sticky_table_headers
2. Open a work item with a long description that contains a markdown table (e.g. a table with several rows)
3. Ensure the description is long enough to trigger the "Read more" truncation (> 80% of viewport height + 96px)
4. Observe that the table sticky-header shadow is no longer visible through the "Read more" gradient overlay

Here's an example that worked for me (while I also have the FF workplan toggled on):

| Col A | Col B |
|---|---|
| short 1 | text 1 |
| short 2 | text 2 |
| short 3 | text 3 |
| short 4 | text 4 |
| short 5 | text 5 |
| short 6 | text 6 |
| short 7 | text 7 |
| short 8 | text 8 |
| short 9 | text 9 |
| short 10 | text 10 |
| short 11 | text 11 |
| short 12 | text 12 |
| short 13 | text 13 |
| short 14 | text 14 |
| short 15 | text 15 |
| short 16 | text 16 |
| short 17 | text 17 |
| short 18 | text 18 |
| short 19 | text 19 |
| short 20 | text 20 |
| short 21 | text 21 |
| short 22 | text 22 |
| short 23 | text 23 |
| short 24 | text 24 |
| short 25 | text 25 |
| short 26 | text 26 |
| short 27 | text 27 |
| short 28 | text 28 |
| short 29 | text 29 |
| short 30 | text 30 |
| short 31 | text 31 |
| short 32 | text 32 |
| short 33 | text 33 |
| short 34 | text 34 |
| short 35 | text 35 |
| short 36 | text 36 |
| short 37 | text 37 |
| short 38 | text 38 |
| short 39 | text 39 |
| short 40 | text 40 |

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.