Do not iterate on CollectionInfoIterator multiple times

As of PHPC-255, we cannot rewind a Cursor. PHPLIB-81 will ultimately change this by caching results; however, there is also no need to assert the iterator count here, since we're asserting the name during iteration (two CollectionInfo results would not share the same name).

Author: jmikola

tests/Database/CollectionManagementFunctionalTest.php

@@ -70,7 +70,6 @@ public function testListCollectionsWithFilter()
 
         $collections = $this->database->listCollections($options);
         $this->assertInstanceOf('MongoDB\Model\CollectionInfoIterator', $collections);
-        $this->assertCount(1, $collections);
 
         foreach ($collections as $collection) {
             $this->assertInstanceOf('MongoDB\Model\CollectionInfo', $collection);