[IndexTable] Conditionally render loadingMarkup on loading prop change

[yurm04]

WHY are these changes introduced?

Updating the loading prop was not rendering the loadingMarkup for the index table loading state

Fixes #11803

WHAT is this pull request doing?

Checking loading to conditionally render loadingMarkup

Screen.Recording.2024-03-29.at.12.14.28.PM.mov

How to 🎩

🖥 Local development instructions
🗒 General tophatting guidelines
📄 Changelog guidelines

🎩 checklist

• Tested a snapshot
• Tested on mobile
• Tested on multiple browsers
• Tested for accessibility
• Updated the component's README.md with documentation changes
• Tophatted documentation changes in the style guide

[LA1CH3]

Hey folks, the changes in this PR effectively eliminate the CSS transition of the loading panel. It just appears and disappears now.

I have a PR up that addresses this by just adding/removing classes and leveraging transition CSS property directly (#11805) but I know @yurm04 was planning on digging into this more to figure out what the root issue with the CSSTransition component is here.

[alex-page]

Can we ship and fix the animation as a follow up? It sucks that this is not rendering anything right now.

[translation-platform]

Localization quality issues found

The following issues may affect the quality of localized translations if they are not addressed:

• The value Clear for key Polaris.ActionList.SearchField.clearButtonLabel is very short. Short strings are more likely to be misunderstood by translators without context. Please provide additional context for the translators if possible.
• The value Search for key Polaris.ActionList.SearchField.search is very short. Short strings are more likely to be misunderstood by translators without context. Please provide additional context for the translators if possible.
• The value Search actions for key Polaris.ActionList.SearchField.placeholder is very short. Short strings are more likely to be misunderstood by translators without context. Please provide additional context for the translators if possible.

Please look out for other instances of this issue in your PR and fix them as well if possible.

Questions about these messages? Hop in the #help-localization Slack channel.

[yurm04]

closing in favor of #11805