Do not try using the cache with values/operator-style conditions

When calling something like:

$backend = node_load(3060)->versioncontrol_project['repo']->getBackend();
$conditions = [
  'branches' => 389286,
  'committer_date' => [
    'operator' => '>',
    'values' => 1494661108,
  ],
];
$backend->loadEntities('operation', [], $conditions);

currently this notice happens:

Undefined property: VersioncontrolGitOperation::$operator controllers.inc:384