[drift] Changed default trial offset from 60 to 90 days per PM reques…

…t. (#156186)

## Summary

Changes the default trial offset used to display the Drift chat
integration from 60 to 90 days.

### Checklist
N/A

### Risk Matrix
N/A

### For maintainers
N/A

(cherry picked from commit fa8096c)

x-pack/plugins/cloud_integrations/cloud_chat/common/constants.ts

@@ -6,4 +6,4 @@
  */
 
 export const GET_CHAT_USER_DATA_ROUTE_PATH = '/internal/cloud/chat_user';
-export const DEFAULT_TRIAL_BUFFER = 60;
+export const DEFAULT_TRIAL_BUFFER = 90;