[8.x] [kbn-grid-layout] Fix mobile styles (#212312) (#212410)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[kbn-grid-layout] Fix mobile styles
(#212312)](#212312)

<!--- Backport version: 9.6.6 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

<!--BACKPORT [{"author":{"name":"Hannah
Mudge","email":"Heenawter@users.noreply.github.com"},"sourceCommit":{"committedDate":"2025-02-25T16:26:26Z","message":"[kbn-grid-layout]
Fix mobile styles (#212312)\n\n## Summary\n\nThis PR fixes a broken
style introduced in\nhttps://github.com//pull/210285
where, when rewriting the\nsingle column styles from strings to objects,
I accidentally set the\nproperty `gridTemplateAreas` instead of
`gridTemplateColumns` - this\nresulted in the single column / mobile
view being broken:\n\n| Before | After
|\n|--------|--------|\n|\n![image](https://github.com/user-attachments/assets/e0541cc7-66dd-41a0-8e21-6931c491cea4)\n|\n![image](https://github.com/user-attachments/assets/12bc1453-1da4-4784-9242-b1cccdf9e24e)\n|\n\n\n###
Checklist\n\n- [x] The PR description includes the appropriate Release
Notes section,\nand the correct `release_note:*` label is applied per
the\n[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)","sha":"464a4714468fa70552e4b110af5fdb17a3e44161","branchLabelMapping":{"^v9.1.0$":"main","^v8.19.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["bug","Feature:Dashboard","Team:Presentation","loe:small","release_note:skip","impact:critical","backport:version","v9.1.0","v8.19.0"],"title":"[kbn-grid-layout]
Fix mobile
styles","number":212312,"url":"https://github.com/elastic/kibana/pull/212312","mergeCommit":{"message":"[kbn-grid-layout]
Fix mobile styles (#212312)\n\n## Summary\n\nThis PR fixes a broken
style introduced in\nhttps://github.com//pull/210285
where, when rewriting the\nsingle column styles from strings to objects,
I accidentally set the\nproperty `gridTemplateAreas` instead of
`gridTemplateColumns` - this\nresulted in the single column / mobile
view being broken:\n\n| Before | After
|\n|--------|--------|\n|\n![image](https://github.com/user-attachments/assets/e0541cc7-66dd-41a0-8e21-6931c491cea4)\n|\n![image](https://github.com/user-attachments/assets/12bc1453-1da4-4784-9242-b1cccdf9e24e)\n|\n\n\n###
Checklist\n\n- [x] The PR description includes the appropriate Release
Notes section,\nand the correct `release_note:*` label is applied per
the\n[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)","sha":"464a4714468fa70552e4b110af5fdb17a3e44161"}},"sourceBranch":"main","suggestedTargetBranches":["8.x"],"targetPullRequestStates":[{"branch":"main","label":"v9.1.0","branchLabelMappingKey":"^v9.1.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/212312","number":212312,"mergeCommit":{"message":"[kbn-grid-layout]
Fix mobile styles (#212312)\n\n## Summary\n\nThis PR fixes a broken
style introduced in\nhttps://github.com//pull/210285
where, when rewriting the\nsingle column styles from strings to objects,
I accidentally set the\nproperty `gridTemplateAreas` instead of
`gridTemplateColumns` - this\nresulted in the single column / mobile
view being broken:\n\n| Before | After
|\n|--------|--------|\n|\n![image](https://github.com/user-attachments/assets/e0541cc7-66dd-41a0-8e21-6931c491cea4)\n|\n![image](https://github.com/user-attachments/assets/12bc1453-1da4-4784-9242-b1cccdf9e24e)\n|\n\n\n###
Checklist\n\n- [x] The PR description includes the appropriate Release
Notes section,\nand the correct `release_note:*` label is applied per
the\n[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)","sha":"464a4714468fa70552e4b110af5fdb17a3e44161"}},{"branch":"8.x","label":"v8.19.0","branchLabelMappingKey":"^v8.19.0$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Hannah Mudge <Heenawter@users.noreply.github.com>

src/platform/packages/private/kbn-grid-layout/grid/grid_layout.tsx

@@ -181,7 +181,7 @@ const styles = {
   singleColumn: css({
     '&.kbnGrid--mobileView': {
       '.kbnGridRow': {
-        gridTemplateAreas: '100%',
+        gridTemplateColumns: '100%',
         gridTemplateRows: 'auto',
         gridAutoFlow: 'row',
         gridAutoRows: 'auto',