[Fleet] Allow back previously disabled bulk actions (elastic#176485)

Patch for elastic#171914

## Summary
In elastic#175318 I had disabled the bulk
actions when the count was incorrect (negative). This was not a good
idea, since some of those actions could still be applied (like
unenrolling) even if the shown count is not correct. Here I'm removing
that check.

### Checklist

- [ ] [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: Kibana Machine <[email protected]>
(cherry picked from commit b620110)

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

@@ -105,7 +105,7 @@ export const AgentBulkActions: React.FunctionComponent<Props> = ({
   const atLeastOneActiveAgentSelected =
     selectionMode === 'manual'
       ? !!selectedAgents.find((agent) => agent.active)
-      : agentCount > 0 && shownAgents > inactiveShownAgents;
+      : shownAgents > inactiveShownAgents;
   const agents = selectionMode === 'manual' ? selectedAgents : selectionQuery;
 
   const [tagsPopoverButton, setTagsPopoverButton] = useState<HTMLElement>();