[FE] Replace "all clusters offline" message (#2773)

* Add message about not existing offline clusters in Dashboard (#2707)

* Review fix

* Review fixes

---------

Co-authored-by: Winnie Chiu <[email protected]>
Co-authored-by: Roman Zabaluev <[email protected]>

Author: winnie-chiu

kafka-ui-react-app/src/components/Brokers/BrokersList/BrokersList.tsx

@@ -193,7 +193,7 @@ const BrokersList: React.FC = () => {
         onRowClick={({ original: { brokerId } }) =>
           navigate(clusterBrokerPath(clusterName, brokerId))
         }
-        emptyMessage="Disk usage data not available"
+        emptyMessage="No clusters are online"
       />
     </>
   );

kafka-ui-react-app/src/components/Brokers/BrokersList/__test__/BrokersList.spec.tsx

@@ -145,7 +145,7 @@ describe('BrokersList Component', () => {
           renderComponent();
           expect(screen.getByRole('table')).toBeInTheDocument();
           expect(
-            screen.getByRole('row', { name: 'Disk usage data not available' })
+            screen.getByRole('row', { name: 'No clusters are online' })
           ).toBeInTheDocument();
         });
       });