Pass Tracer.Instance to Cache

Necessary as otherwise we won't disable the
commands.

tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/AdoNet/DbScopeFactory.cs

@@ -249,7 +249,7 @@ static Cache()
             {
                 CommandType = typeof(TCommand);
 
-                if (TryGetIntegrationDetails(CommandType.FullName, tracer: null, out var integrationId, out var dbTypeName))
+                if (TryGetIntegrationDetails(CommandType.FullName, tracer: Tracer.Instance, out var integrationId, out var dbTypeName))
                 {
                     // cache values for this TCommand type
                     DbTypeName = dbTypeName;