[Security Solution] [Grouping] Re-add support to custom Group By titl…

…e in the useGetGroupSelector hook (#184165)

## Summary

This PR fixes a regression from PR #180016 where the support to the
custom title on the `useGetGroupSelector` hook was dropped and the
Findings DataTables was displaying "Group alerts by" instead of "Group
findings by". Unit tests were added to prevent further regressions.


## Screenshots


![image](https://github.com/elastic/kibana/assets/19270322/97ac29f7-d314-4df9-a4d8-9a11b198f021)


![image](https://github.com/elastic/kibana/assets/19270322/6e6a3eef-fd4e-4619-a460-a3b0fb46ec37)


![image](https://github.com/elastic/kibana/assets/19270322/e6bcd40c-45e6-4444-8905-7c7c2c900926)

packages/kbn-grouping/src/components/group_selector/index.test.tsx

@@ -73,6 +73,14 @@ describe('group selector', () => {
     const { getByTestId } = render(<GroupSelector {...testProps} />);
     expect(getByTestId('group-selector-dropdown').textContent).toBe('Group alerts by: Rule name');
   });
+  it('Sets the Group by title from the title prop', () => {
+    const { getByTestId } = render(
+      <GroupSelector {...testProps} title="Group custom property by" />
+    );
+    expect(getByTestId('group-selector-dropdown').textContent).toBe(
+      'Group custom property by: Rule name'
+    );
+  });
   it('Presents correct option when group selector dropdown is clicked', () => {
     const { getByTestId } = render(<GroupSelector {...testProps} />);
     fireEvent.click(getByTestId('group-selector-dropdown'));

packages/kbn-grouping/src/hooks/use_get_group_selector.test.tsx

@@ -376,6 +376,17 @@ describe('Group Selector Hooks', () => {
         type: ActionType.updateGroupOptions,
       });
     });
+
+    it('Supports custom group by title', () => {
+      const result = renderHook(() =>
+        useGetGroupSelector({
+          ...defaultArgs,
+          title: 'Group custom property by',
+        })
+      );
+
+      expect(result.result.current.props.title).toEqual('Group custom property by');
+    });
   });
 
   describe('useGetGroupSelectorStateless', () => {

packages/kbn-grouping/src/hooks/use_get_group_selector.tsx

@@ -211,8 +211,9 @@ export const useGetGroupSelector = ({
           fields,
           maxGroupingLevels,
           options,
+          title,
         }}
       />
     );
-  }, [groupingId, fields, maxGroupingLevels, onChange, selectedGroups, options]);
+  }, [groupingId, fields, maxGroupingLevels, onChange, selectedGroups, options, title]);
 };