WWT.Web: don't report missing tour blobs as App Insights errors

Relevant to WorldWideTelescope#276. This is external user input so there will be bogus
values.

src/WWT.Web/WwtTelemetryProcessor.cs

@@ -27,15 +27,19 @@ private void MaybeModify(ITelemetry item)
             if (dep == null)
                 return;
 
-            // Don't report missing thumbnails as App Insights errors. That's
-            // just how our system works. The docs for `DependencyTelemetry` are
-            // not helpful on their own, but you can go into the Azure Logs
-            // interface for App Insights and do queries on the `dependencies`
-            // table to see what fields correspond to what UI elements.
+            // Don't report missing thumbnails or tours as App Insights errors.
+            // That's just how our system works. The docs for
+            // `DependencyTelemetry` are not helpful on their own, but you can
+            // go into the Azure Logs interface for App Insights and do queries
+            // on the `dependencies` table to see what fields correspond to what
+            // UI elements.
 
             if (dep.ResultCode == "404" && dep.Data.StartsWith("https://wwtfiles.blob.core.windows.net/thumbnails/"))
                 dep.Success = true;
 
+            if (dep.ResultCode == "404" && dep.Data.StartsWith("https://wwtfiles.blob.core.windows.net/coretours/"))
+                dep.Success = true;
+
             if (dep.Name == "BlobBaseClient.Exists")
                 // Unfortunately I don't see a way to make this filter more specific.
                 dep.Success = true;