[Security Solution] Risk score area chart displayed error (#155597)

## Summary

Risk score area chart displayed error on host details page:
/app/security/hosts/name/{hostName}/hostRisk

Before:
![Screenshot 2023-04-24 at 11 02
19](https://user-images.githubusercontent.com/6295984/233961792-7f8c64f6-0bbb-467d-b762-0b9cbf86a979.png)

After:
<img width="834" alt="Screenshot 2023-04-24 at 10 21 55"
src="https://user-images.githubusercontent.com/6295984/233961617-b78e1c05-6b9f-406a-8264-e615cf8e4848.png">

Relevant changes:
https://github.com/elastic/kibana/pull/152506/files#diff-260dbbbd965ff10673ef7670e2cb819173662b51bb353b7ad702a60334e874ff


### Checklist

Delete any items that are not applicable to this PR.


- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

x-pack/plugins/security_solution/public/common/components/visualization_actions/lens_attributes/common/risk_scores/__snapshots__/risk_score_over_time_area.test.ts.snap

@@ -184,7 +184,7 @@ Object {
               "color": "#aa6556",
               "fill": "none",
               "forAccessor": "1dd5663b-f062-43f8-8688-fc8166c2ca8e",
-              "icon": "warning",
+              "icon": "alert",
               "iconPosition": "left",
               "lineWidth": 2,
               "textVisibility": true,

x-pack/plugins/security_solution/public/common/components/visualization_actions/lens_attributes/common/risk_scores/risk_score_over_time_area.test.ts

@@ -6,6 +6,7 @@
  */
 
 import { renderHook } from '@testing-library/react-hooks';
+import type { XYState } from '@kbn/lens-plugin/public';
 import { wrapper } from '../../../mocks';
 
 import { useLensAttributes } from '../../../use_lens_attributes';
@@ -56,4 +57,42 @@ describe('getRiskScoreOverTimeAreaAttributes', () => {
 
     expect(result?.current).toMatchSnapshot();
   });
+
+  it('should render a Reference Line with an Alert icon', () => {
+    const { result } = renderHook(
+      () =>
+        useLensAttributes({
+          getLensAttributes: getRiskScoreOverTimeAreaAttributes,
+          stackByField: 'host',
+          extraOptions: {
+            spaceId: 'mockSpaceId',
+          },
+        }),
+      { wrapper }
+    );
+
+    expect(
+      (result?.current?.state.visualization as XYState).layers.find(
+        (layer) => layer.layerType === 'referenceLine'
+      )
+    ).toEqual(
+      expect.objectContaining({
+        layerId: '1dd5663b-f062-43f8-8688-fc8166c2ca8e',
+        layerType: 'referenceLine',
+        accessors: ['1dd5663b-f062-43f8-8688-fc8166c2ca8e'],
+        yConfig: [
+          {
+            forAccessor: '1dd5663b-f062-43f8-8688-fc8166c2ca8e',
+            axisMode: 'left',
+            lineWidth: 2,
+            color: '#aa6556',
+            icon: 'alert',
+            textVisibility: true,
+            fill: 'none',
+            iconPosition: 'left',
+          },
+        ],
+      })
+    );
+  });
 });

x-pack/plugins/security_solution/public/common/components/visualization_actions/lens_attributes/common/risk_scores/risk_score_over_time_area.ts

@@ -56,7 +56,7 @@ export const getRiskScoreOverTimeAreaAttributes: GetLensAttributes = (
                 axisMode: 'left',
                 lineWidth: 2,
                 color: '#aa6556',
-                icon: 'warning',
+                icon: 'alert',
                 textVisibility: true,
                 fill: 'none',
                 iconPosition: 'left',