Remove hovercards from Feed panels on dashboards

Summary:
Fixes T5472.

I do imagine doing a pass on the Hovercard JS at some point to try to make them position more intelligently (I've hit a few cases where they do something silly, and we can probably fix many of them), but generally agree that this is inconsistent and questionably valuable on panels.

Test Plan:
  - Moused over feed stuff in a panel, no hovercards.
  - Moused over feed stuff in Feed, got hovercards.

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T5472

Differential Revision: https://secure.phabricator.com/D9753

src/applications/feed/query/PhabricatorFeedSearchEngine.php

@@ -134,7 +134,13 @@ final class PhabricatorFeedSearchEngine
     array $handles) {
 
     $builder = new PhabricatorFeedBuilder($objects);
-    $builder->setShowHovercards(true);
+
+    if ($this->isPanelContext()) {
+      $builder->setShowHovercards(false);
+    } else {
+      $builder->setShowHovercards(true);
+    }
+
     $builder->setUser($this->requireViewer());
     $view = $builder->buildView();