[Dashboard] Add styling to allow clickable TSVB markdown images (elas…

…tic#147802)

## Summary

After upgrading to [React
17](elastic#128239), the old version of
`react-grid-layout` was no longer compatible and required an upgrade as
well. However, this upgrade included a
[PR](react-grid-layout/react-grid-layout#1283)
that overcame a visual glitch with images, which made it so that a
clickable image in TSVB markdown was only clickable in a small region at
the bottom of the image.

This PR fixes this by undoing the changes made in the aforementioned
[PR](react-grid-layout/react-grid-layout#1283)
specifically for TSVB markdown images.

### Videos

**Before**


https://user-images.githubusercontent.com/8698078/208514574-e586c1e0-3675-4ef2-9a42-9956f81dee5a.mov


**After**


https://user-images.githubusercontent.com/8698078/208514585-353a0413-7ed2-40f9-8e90-8289b5483ecb.mov



### Checklist

- [x] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)


### For maintainers

- [ ] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

Co-authored-by: Kibana Machine <[email protected]>

src/plugins/kibana_react/public/markdown/_markdown.scss

@@ -143,6 +143,7 @@ $kbnDefaultFontSize: 14px;
     max-width: 100%;
     box-sizing: content-box;
     border-style: none;
+    pointer-events: auto;
   }
 
   // 4. Blockquotes