sp_QuickieStore: use EXISTS pattern in final plan OUTER APPLY

The JOIN pattern in the OUTER APPLY wasn't getting a good plan.
EXISTS with the semi-join against #hi_id_staging_plans lets the
optimizer pick a better strategy for the correlated subquery.

Tested on SQL2022.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: erikdarlingdata

sp_QuickieStore/sp_QuickieStore.sql

@@ -5606,10 +5606,15 @@ OUTER APPLY
                         qsp.last_execution_time DESC
                 ),
             qsp.query_plan
-        FROM #hi_id_staging_plans AS sp
-        JOIN ' + @database_name_quoted + N'.sys.query_store_plan AS qsp
-            ON qsp.plan_id = sp.plan_id
-        WHERE sp.query_hash = o.query_hash
+        FROM ' + @database_name_quoted + N'.sys.query_store_plan AS qsp
+        WHERE EXISTS
+        (
+            SELECT
+                1/0
+            FROM #hi_id_staging_plans AS sp
+            WHERE qsp.plan_id = sp.plan_id
+            AND   sp.query_hash = o.query_hash
+        )
     ) AS qp0
     WHERE qp0.n = 1
 ) AS qp