[9.0] [Synthetics] Fixed layout when monitors are grouped by (#216434) (#216882)

# Backport

This will backport the following commits from `main` to `9.0`:
- [[Synthetics] Fixed layout when monitors are grouped by
(#216434)](https://github.com/elastic/kibana/pull/216434)

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

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

<!--BACKPORT [{"author":{"name":"Francesco
Fagnani","email":"fagnani.francesco@gmail.com"},"sourceCommit":{"committedDate":"2025-04-02T07:27:10Z","message":"[Synthetics]
Fixed layout when monitors are grouped by (#216434)\n\nThis PR closes
#207560.\n\nBefore:\n<img width=\"1512\" alt=\"Screenshot 2025-03-31 at
12 01
55\"\nsrc=\"https://github.com/user-attachments/assets/eee8e848-0df5-45af-a53d-8ee3c24a84fc\"\n/>\n\nAfter:\n<img
width=\"1512\" alt=\"Screenshot 2025-03-31 at 12 02
19\"\nsrc=\"https://github.com/user-attachments/assets/841b537e-4f55-40e1-b76f-4492812f2da3\"\n/>","sha":"bb397ccd9ee2fa72f168468dbcc2c65daa71a228","branchLabelMapping":{"^v9.1.0$":"main","^v8.19.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","Team:obs-ux-management","backport:version","v9.1.0","v8.19.0","v9.0.1"],"title":"[Synthetics]
Fixed layout when monitors are grouped
by","number":216434,"url":"https://github.com/elastic/kibana/pull/216434","mergeCommit":{"message":"[Synthetics]
Fixed layout when monitors are grouped by (#216434)\n\nThis PR closes
#207560.\n\nBefore:\n<img width=\"1512\" alt=\"Screenshot 2025-03-31 at
12 01
55\"\nsrc=\"https://github.com/user-attachments/assets/eee8e848-0df5-45af-a53d-8ee3c24a84fc\"\n/>\n\nAfter:\n<img
width=\"1512\" alt=\"Screenshot 2025-03-31 at 12 02
19\"\nsrc=\"https://github.com/user-attachments/assets/841b537e-4f55-40e1-b76f-4492812f2da3\"\n/>","sha":"bb397ccd9ee2fa72f168468dbcc2c65daa71a228"}},"sourceBranch":"main","suggestedTargetBranches":["9.0"],"targetPullRequestStates":[{"branch":"main","label":"v9.1.0","branchLabelMappingKey":"^v9.1.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/216434","number":216434,"mergeCommit":{"message":"[Synthetics]
Fixed layout when monitors are grouped by (#216434)\n\nThis PR closes
#207560.\n\nBefore:\n<img width=\"1512\" alt=\"Screenshot 2025-03-31 at
12 01
55\"\nsrc=\"https://github.com/user-attachments/assets/eee8e848-0df5-45af-a53d-8ee3c24a84fc\"\n/>\n\nAfter:\n<img
width=\"1512\" alt=\"Screenshot 2025-03-31 at 12 02
19\"\nsrc=\"https://github.com/user-attachments/assets/841b537e-4f55-40e1-b76f-4492812f2da3\"\n/>","sha":"bb397ccd9ee2fa72f168468dbcc2c65daa71a228"}},{"branch":"8.x","label":"v8.19.0","branchLabelMappingKey":"^v8.19.0$","isSourceBranch":false,"url":"https://github.com/elastic/kibana/pull/216750","number":216750,"state":"MERGED","mergeCommit":{"sha":"12bb59fa8f48d0c2ac529caad0f58fa09308f365","message":"[8.x]
[Synthetics] Fixed layout when monitors are grouped by (#216434)
(#216750)\n\n# Backport\n\nThis will backport the following commits from
`main` to `8.x`:\n- [[Synthetics] Fixed layout when monitors are grouped
by\n(#216434)](https://github.com/elastic/kibana/pull/216434)\n\n\n\n###
Questions ?\nPlease refer to the [Backport
tool\ndocumentation](https://github.com/sorenlouv/backport)\n\n\n\nCo-authored-by:
Francesco Fagnani
<fagnani.francesco@gmail.com>"}},{"branch":"9.0","label":"v9.0.1","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Francesco Fagnani <fagnani.francesco@gmail.com>

x-pack/solutions/observability/plugins/synthetics/public/apps/synthetics/components/monitors_page/overview/overview/overview_grid.tsx

@@ -150,7 +150,7 @@ export const OverviewGrid = memo(() => {
         </EuiFlexItem>
       </EuiFlexGroup>
       <EuiSpacer size="m" />
-      <div style={{ height: listHeight }}>
+      <div style={groupField === 'none' ? { height: listHeight } : undefined}>
         {groupField === 'none' ? (
           loaded && monitorsSortedByStatus.length ? (
             <EuiAutoSizer>