don't fail the external feed job on insecure url

fixes CNVS-39953

test plan:
- try to enter an blacklisted url as an external feed
- the job should still run

Change-Id: I302203b2f1502ca9bf767916b2287649a3cb0f63
Reviewed-on: https://gerrit.instructure.com/129746
Tested-by: Jenkins
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>
QA-Review: Simon Williams <simon@instructure.com>

lib/external_feed_aggregator.rb

@@ -93,7 +93,13 @@ class ExternalFeedAggregator
         @logger.info("request failed #{response.class}")
         handle_failure(feed)
       end
-    rescue CanvasHttp::Error, CanvasHttp::RelativeUriError, Timeout::Error, SocketError, SystemCallError => e
+    rescue CanvasHttp::Error,
+      CanvasHttp::RelativeUriError,
+      CanvasHttp::InsecureUriError,
+      Timeout::Error,
+      SocketError,
+      SystemCallError => e
+
       @logger.info("request error: #{e}")
       handle_failure(feed)
     end