Remove "in site pool" option from pool settings

It's nonfunctional anyway; we throw that key out when calculating a pool
to avoid issues of recursion. The key only works for a regular search.

(fix #1461)

application/view/common/advanced-search.phtml

@@ -4,6 +4,7 @@ $this->headScript()->appendFile($this->assetUrl('js/advanced-search.js', 'Omeka'
 
 $query = isset($query) ? $query : null;
 $resourceType = isset($resourceType) ? $resourceType : null;
+$isPool = isset($isPool) ? $isPool : null;
 
 $partials = [
     'common/advanced-search/fulltext',
@@ -16,7 +17,7 @@ if ($this->status()->isAdminRequest()) {
 switch ($resourceType) {
     case 'item':
         $partials[] = 'common/advanced-search/item-sets';
-        if ($this->status()->isAdminRequest()) {
+        if ($this->status()->isAdminRequest() && !$isPool) {
             $partials[] = 'common/advanced-search/site-pool';
         }
         break;

application/view/omeka/site-admin/index/resources.phtml

@@ -46,7 +46,7 @@ $rowTemplate = '
     ); ?></p>
     <div id="advanced-search"><?php echo $this->partial(
         'common/advanced-search',
-        ['query' => $site->itemPool(), 'resourceType' => 'item']
+        ['query' => $site->itemPool(), 'resourceType' => 'item', 'isPool' => true]
     ); ?></div>
 </div>