Log and continue when trying to destroy edges with no edge definition

Summary: Fixes T11201.

Test Plan:
Created bogus edges like this:

```
INSERT INTO edge (src, type, dst, dateCreated, seq) values ('PHID-TASK-vnddativbialb5p6ymis', 999999, 'quack', UNIX_TIMESTAMP(), 1);
```

Then ran `bin/remove destroy` on the relevant object.

Before the patch, destruction halted after hittin the bad edge.

After the patch, a warning is emitted but destruction continues.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11201

Differential Revision: https://secure.phabricator.com/D16171

src/infrastructure/edges/engineextension/PhabricatorEdgesDestructionEngineExtension.php

@@ -28,10 +28,20 @@ final class PhabricatorEdgesDestructionEngineExtension
     foreach ($edges as $type => $type_edges) {
       foreach ($type_edges as $src => $src_edges) {
         foreach ($src_edges as $dst => $edge) {
+          try {
             $editor->removeEdge($edge['src'], $edge['type'], $edge['dst']);
+          } catch (Exception $ex) {
+            // We can run into an exception while removing the edge if the
+            // edge type no longer exists. This prevents us from figuring out
+            // if there's an inverse type. Just ignore any errors here and
+            // continue, since the best we can do is clean up all the edges
+            // we still have information about. See T11201.
+            phlog($ex);
           }
         }
       }
+    }
+
     $editor->save();
   }