[PM-20041] Deleting Notifications when Task is completed (#5896)

* mark all notifications associated with a security task as deleted when the task is completed

* fix spelling

* formatting

* refactor "Active" to "NonDeleted"

* refactor "Active" to "NonDeleted" for stored procedure

* only send notifications per user for each notification

* move notification status updates into the DB layer to save on multiple queries and insertions from the C#

* Only return UserIds from db layer

* omit userId from `MarkTaskAsCompletedCommand` query.

The userId from the notification will be used

* update UserIds

* consistency in comments regarding `taskId` and `UserId`

util/Migrator/DbScripts/2025-05-30_00_Notification_MarkAsDeletedByTask.sql

@@ -0,0 +1,35 @@
+CREATE OR ALTER PROCEDURE [dbo].[Notification_MarkAsDeletedByTask]
+    @TaskId UNIQUEIDENTIFIER
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    -- Collect UserIds as they are altered
+    DECLARE @UserIdsForAlteredNotifications TABLE (
+        UserId UNIQUEIDENTIFIER
+    );
+
+    -- Update existing NotificationStatus as deleted
+    UPDATE ns
+    SET ns.DeletedDate = GETUTCDATE()
+    OUTPUT inserted.UserId INTO @UserIdsForAlteredNotifications
+    FROM NotificationStatus ns
+    INNER JOIN Notification n ON ns.NotificationId = n.Id
+    WHERE n.TaskId = @TaskId
+      AND ns.DeletedDate IS NULL;
+
+    -- Insert NotificationStatus records for notifications that don't have one yet
+    INSERT INTO NotificationStatus (NotificationId, UserId, DeletedDate)
+    OUTPUT inserted.UserId INTO @UserIdsForAlteredNotifications
+    SELECT n.Id, n.UserId, GETUTCDATE()
+    FROM Notification n
+    LEFT JOIN NotificationStatus ns
+        ON n.Id = ns.NotificationId
+    WHERE n.TaskId = @TaskId
+      AND ns.NotificationId IS NULL;
+
+    -- Return the UserIds associated with the altered notifications
+    SELECT u.UserId
+    FROM @UserIdsForAlteredNotifications u;
+END
+GO