Stop flashing opacity of issue description on details expand/collapse

What does this MR do and why?

When checkboxes are marked done in an issue description, the page flashes an animation to indicate a change. For <details> html tags opening and closing, this animation is distracting & unnecessary because the issue description hasn't actually changed.

This MR removes the animation when the only description change is whether <details> elements are open/closed.

Screenshots or screen recordings

Before	After
Animation_of_details_toggle	Removed_animation_for_details

How to set up and validate locally

1. Create an issue with a description like:

<details><summary>Test this open close thing</summary>

with content insideeeee

| a table | header |
| ------ | ------ |
|        |        |
|        |    maybe    |

</details>

<details><summary>Test this open close thing</summary>

with content insideeeee

| a table | header |
| ------ | ------ |
|        |        |
|        |    maybe    |

</details>

- [x] lets add a task

2. Interact with stuff a few times

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.