[Security Solution] Update SIEM/Endpoint tour copy (#160567)

## Summary

Update Copy in SIEM tour for adding Elastic Defend integration.


### Checklist

- [x] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/packages/kbn-i18n/README.md)

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

x-pack/plugins/fleet/public/components/with_guided_onboarding_tour.tsx

@@ -19,8 +19,7 @@ const getTourConfig = (packageKey: string, tourType: TourType) => {
         defaultMessage: 'Add Elastic Defend',
       }),
       description: i18n.translate('xpack.fleet.guidedOnboardingTour.endpointButton.description', {
-        defaultMessage:
-          'In just a few steps, add your data with our recommended defaults. You can change this later.',
+        defaultMessage: `In this workflow, we'll be using Elastic Defend only to collect data for SIEM. Installing this will not conflict with existing endpoint security products.`,
       }),
     };
   }