Remove pointless WAITFOR DECOMPRESS filters from stats/store queries

The CAST(DECOMPRESS(...)) NOT LIKE N'WAITFOR%' filter was decompressing
query text on every row in query_stats and query_store_data just to skip
WAITFOR queries. WAITFOR has no plan and no meaningful stats — it only
matters in query snapshots (active sessions), where the filter remains.

On a 742K-row query_stats table, this was a significant contributor to
the 120-second query timeouts reported in #835.

The snapshot filters (report.query_snapshots) and MCP phased queries
are untouched — they filter after TOP on already-hydrated text.

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

Author: erikdarlingdata

Dashboard/Services/DatabaseService.QueryPerformance.cs

@@ -1104,7 +1104,6 @@ FROM collect.query_stats AS qs
                     OR (qs.last_execution_time >= @fromDate AND qs.last_execution_time <= @toDate)
                     OR (qs.creation_time <= @fromDate AND qs.last_execution_time >= @toDate)))
             )
-            AND CAST(DECOMPRESS(qs.query_text) AS nvarchar(max)) NOT LIKE N'WAITFOR%'
             GROUP BY
                 qs.database_name,
                 qs.query_hash,
@@ -1477,7 +1476,7 @@ USE HINT('ENABLE_PARALLEL_PLAN_PREFERENCE')
     ISNULL(SUM(qsd.avg_physical_io_reads * qsd.count_executions), 0) AS total_physical_reads,
     ISNULL(SUM(qsd.avg_logical_io_writes * qsd.count_executions), 0) AS total_writes
 FROM collect.query_store_data AS qsd
-WHERE CAST(DECOMPRESS(qsd.query_sql_text) AS nvarchar(max)) NOT LIKE N'WAITFOR%'
+WHERE 1 = 1
 {timeFilter}
 GROUP BY DATEADD(HOUR, DATEDIFF(HOUR, 0, qsd.collection_time), 0)
 ORDER BY bucket_hour;";
@@ -1580,7 +1579,6 @@ FROM collect.query_store_data AS qsd
                 OR (qsd.server_last_execution_time >= @fromDate AND qsd.server_last_execution_time <= @toDate)
                 OR (qsd.server_first_execution_time <= @fromDate AND qsd.server_last_execution_time >= @toDate)))
         )
-        AND CAST(DECOMPRESS(qsd.query_sql_text) AS nvarchar(max)) NOT LIKE N'WAITFOR%'
         GROUP BY
             qsd.database_name,
             qsd.query_id