Fix error displayed when insights files can't be found and fix server-report insights in dev build (#18635)

* Fix error

* fix queries

extensions/server-report/sql/metadataContention.sql

@@ -0,0 +1,22 @@
+--SQL script to grab metadata contention from histogram
+Use tempdb
+DECLARE @target_data XML;
+SELECT @target_data = CAST(t.target_data AS XML)
+FROM sys.dm_xe_sessions AS s
+JOIN sys.dm_xe_session_targets AS t
+    ON t.event_session_address = s.address
+WHERE s.name = N'ObjectContention' and t.target_name = N'histogram';
+
+with wait_stats as
+(
+SELECT
+    n.value('(value)[1]','bigint') AS alloc_unit_id,
+    n.value('(@count)[1]', 'bigint') AS [Count]
+FROM @target_data.nodes('//HistogramTarget/Slot') AS q(n)
+)
+
+SELECT objects.id,  SUM(objects.count) as [Count] FROM 
+    (SELECT [dbo].[isSystemTable](wait_stats.alloc_unit_id) AS id, wait_stats.Count AS [count]
+    FROM wait_stats
+    WHERE [dbo].[isSystemTable](wait_stats.alloc_unit_id) not in (0, 99)) AS objects
+GROUP BY objects.id