Update connection string

Author: sebastienros

frameworks/CSharp/aspnetcore/appsettings.postgresql.json

@@ -1,4 +1,4 @@
 {
-  "ConnectionString": "Server=tfb-database;Database=hello_world;User Id=benchmarkdbuser;Password=benchmarkdbpass;SSL Mode=Disable;Maximum Pool Size=512;NoResetOnClose=true;Enlist=false;Max Auto Prepare=4",
+  "ConnectionString": "Server=tfb-database;Database=hello_world;User Id=benchmarkdbuser;Password=benchmarkdbpass;SSL Mode=Disable;Maximum Pool Size=18;Enlist=false;Max Auto Prepare=4;Multiplexing=true;Write Coalescing Buffer Threshold Bytes=1000;",
   "Database": "postgresql"
 }

frameworks/CSharp/aspnetcore/src/Platform/Data/RawDbNpgsql.cs

@@ -138,11 +138,10 @@ public async Task<World[]> LoadMultipleUpdatesRows(int count)
 
         // Ensure unique ids by incrementing duplicates
         for (var i = 1; i < count; i++)
-            if (ids[i] <= ids[i - 1])
-                ids[i] = Math.Min(ids[i - 1] + 1, 10000);
+            if (ids[i] == ids[i - 1])
+                ids[i] = (ids[i] % 10000) + 1;
 
-        using var connection = CreateConnection();
-        await connection.OpenAsync();
+        using var connection = await _dataSource.OpenConnectionAsync();
 
         // Each row must be selected randomly using one query in the same fashion as the single database query test
         // Use of IN clauses or similar means to consolidate multiple queries into one operation is not permitted.