fix: stop updating agent stats from deleted workspaces (#11026)

Co-authored-by: Steven Masley <stevenmasley@gmail.com>

coderd/database/queries/workspaceagents.sql

@@ -252,9 +252,10 @@ FROM users
 WHERE
 	-- TODO: we can add more conditions here, such as:
 	-- 1) The user must be active
-	-- 2) The user must not be deleted
-	-- 3) The workspace must be running
+	-- 2) The workspace must be running
 	workspace_agents.auth_token = @auth_token
+AND
+	workspaces.deleted = FALSE
 GROUP BY
 	workspace_agents.id,
 	workspaces.id,