[Fleet] fix for kuery error on Agent list UI (#162816)

## Summary

Fix #160493

Fixed logic that queried managed agents to exclude them from bulk
actions. It was not working properly if there are no managed agent
policies.

To verify:
- Enroll 10 agents with horde
- Limit rows per page to 5
- Select an agent policy that has more then 5 agents
- Select everything on all pages
- Check Network tab in Chrome Dev Tools that there is no error anymore
in /agents API call

<img width="2086" alt="image"
src="https://github.com/elastic/kibana/assets/90178898/d8292a54-d443-4c0d-9111-f37975529561">



### Checklist

- [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

x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/components/bulk_actions.test.tsx

@@ -257,6 +257,43 @@ describe('AgentBulkActions', () => {
       ).toBeEnabled();
     });
 
+    it('should show correct actions when no managed policies exist', async () => {
+      const selectedAgents: Agent[] = [];
+      mockedSendGetAgentPolicies.mockResolvedValue({
+        data: {
+          items: [],
+        },
+      });
+
+      const props = {
+        totalAgents: 10,
+        totalInactiveAgents: 0,
+        selectionMode: 'query',
+        currentQuery: '(Base query)',
+        selectedAgents,
+        visibleAgents: [],
+        refreshAgents: () => undefined,
+        allTags: [],
+        agentPolicies: [],
+      };
+      const results = render(props);
+
+      const bulkActionsButton = results.getByTestId('agentBulkActionsButton');
+
+      await act(async () => {
+        fireEvent.click(bulkActionsButton);
+      });
+
+      expect(results.getByText('Add / remove tags').closest('button')!).toBeEnabled();
+      expect(results.getByText('Assign to new policy').closest('button')!).toBeEnabled();
+      expect(results.getByText('Unenroll 10 agents').closest('button')!).toBeEnabled();
+      expect(results.getByText('Upgrade 10 agents').closest('button')!).toBeEnabled();
+      expect(results.getByText('Schedule upgrade for 10 agents').closest('button')!).toBeDisabled();
+      expect(
+        results.getByText('Request diagnostics for 10 agents').closest('button')!
+      ).toBeEnabled();
+    });
+
     it('should generate a correct kuery to select agents', async () => {
       mockedSendGetAgentPolicies.mockResolvedValue({
         data: {

x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/components/bulk_actions.tsx

@@ -96,6 +96,10 @@ export const AgentBulkActions: React.FunctionComponent<Props> = ({
 
       const managedPolicies = agentPoliciesResponse.data?.items ?? [];
 
+      if (managedPolicies.length === 0) {
+        return [];
+      }
+
       // find all the agents that have those policies and are not unenrolled
       const policiesKuery = managedPolicies
         .map((policy) => `policy_id:"${policy.id}"`)