[Fleet] Missing policy filter in Fleet Server check to enable secrets (#187935)

## Summary

Closes https://github.com/elastic/kibana/issues/187933
Closes https://github.com/elastic/kibana/issues/186845

Fixed missing policy filter when checking if Fleet Servers met minimum
version to enable secrets storage.
The integration tests cover now a case where there are no fleet servers
but there are agents with minimum version, to verify that the query
filters them out.

Manual verification is hard because you can't enroll an agent without
enrolling FS with at least the same version.
It could be done by manually creating docs in `.fleet-agents`.

### 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/server/services/fleet_server/index.test.ts

@@ -115,6 +115,13 @@ describe('checkFleetServerVersionsForSecretsStorage', () => {
       version
     );
     expect(result).toBe(true);
+    expect(mockedGetAgentsByKuery).toHaveBeenCalledWith(
+      esClientMock,
+      soClientMock,
+      expect.objectContaining({
+        kuery: 'policy_id:("1" or "2")',
+      })
+    );
   });
 });
 

x-pack/plugins/fleet/server/services/fleet_server/index.ts

@@ -128,11 +128,19 @@ export async function checkFleetServerVersionsForSecretsStorage(
       hasMore = false;
     }
   }
+  if (policyIds.size === 0) {
+    return false;
+  }
+
+  const kuery = `policy_id:(${Array.from(policyIds)
+    .map((id) => `"${id}"`)
+    .join(' or ')})`;
 
   const managedAgentPolicies = await agentPolicyService.getAllManagedAgentPolicies(soClient);
   const fleetServerAgents = await getAgentsByKuery(esClient, soClient, {
     showInactive: true,
     perPage: SO_SEARCH_LIMIT,
+    kuery,
   });
 
   if (fleetServerAgents.agents.length === 0) {

x-pack/test/fleet_api_integration/apis/policy_secrets.ts

@@ -847,6 +847,8 @@ export default function (providerContext: FtrProviderContext) {
       it('should not store secrets if fleet server does not meet minimum version', async () => {
         const { fleetServerAgentPolicy } = await createFleetServerAgentPolicy();
         await createFleetServerAgent(fleetServerAgentPolicy.id, 'server_1', '7.0.0');
+        const { fleetServerAgentPolicy: fleetServerPolicy2 } = await createFleetServerAgentPolicy(); // extra policy to verify `or` condition
+        await createFleetServerAgent(fleetServerPolicy2.id, 'server_1', '8.12.0');
 
         await callFleetSetup();
 
@@ -865,7 +867,10 @@ export default function (providerContext: FtrProviderContext) {
       });
 
       it('should not store secrets if there are no fleet servers', async () => {
+        await createFleetServerAgentPolicy();
         const agentPolicy = await createAgentPolicy();
+        // agent with new version shouldn't make storage secrets enabled
+        await createFleetServerAgent(agentPolicy.id, 'server_2', '8.12.0');
         const packagePolicyWithSecrets = await createPackagePolicyWithSecrets(agentPolicy.id);
 
         // secret should be in plain text i.e not a secret refrerence