Update maintenance-scheduling.md

Remove the below incorrect sentence.

A 24-hour advance notification precedes all maintenance events that aren't for the DW400c and lower tiers.

Author: dialmoth

articles/synapse-analytics/sql-data-warehouse/maintenance-scheduling.md

@@ -32,8 +32,6 @@ All maintenance operations should finish within the specified maintenance window
 
 Integration with Service Health notifications and the Resource Health Check Monitor allows customers to stay informed of impending maintenance activity. This automation takes advantage of Azure Monitor. You can decide how you want to be notified of impending maintenance events. Also, you can choose which automated flows will help you manage downtime and minimize operational impact.
 
-A 24-hour advance notification precedes all maintenance events that aren't for the DW400c and lower tiers.
-
 > [!NOTE]
 > In the event we are required to deploy a time critical update, advanced notification times may be significantly reduced. This could occur outside an identified maintenance window due to the critical nature of the update.