Follow up: Move db queries in AggregatorFeedBlock to FeedStorageController

also as part of #2068325: [META] Convert entity SQL queries to the Entity Query API (we already have a major open for this)

1. +++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/AggregatorFeedBlock.php
   @@ -81,7 +82,7 @@ public function getDerivativeDefinition($derivative_id, array $base_plugin_defin
   -    $result = $this->connection->query('SELECT fid, title, block FROM {aggregator_feed} WHERE block <> 0 AND fid = :fid', array(':fid' => $derivative_id))->fetchObject();
   

   so the more i look at this query the more i think we can replace this with just an aggregator_feed_load($derivative_id) and then just check $feed->block->value and bail out

2. +++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/AggregatorFeedBlock.php
   @@ -93,7 +94,7 @@ public function getDerivativeDefinition($derivative_id, array $base_plugin_defin
   -    $result = $this->connection->query('SELECT fid, title FROM {aggregator_feed} WHERE block <> 0 ORDER BY fid');
   +    $result = $this->feedStorage->loadAllFeedBlocks();
   

   This i would call it loadBlockEnabled()

3. Not sure how to do the entity query stuff

   Those methods from the feed storage should return a full loaded entity, so we can also standarize on calls like id() or label()..fetchObject only gives an stdClass.
   You can check \Drupal\aggregator\Form\OpmlFeedAdd to see how ti works

Finally though:

I noticed that #1888702: Use configuration selection instead of derivatives for some blocks kills both those queries and i think it will eventually get in, so we should probably postpone this issue

yeap, those classes where removed