B2B-2658: Implement GraphQL Resolver Cache for Customer query

- is_subscribed cache test

Author: rganin

dev/tests/api-functional/testsuite/Magento/GraphQl/CustomerGraphQl/Model/Resolver/CustomerTest.php

@@ -177,7 +177,7 @@ public function testCustomerIsSubscribedResolverCacheAndInvalidation()
         $this->assertIsSubscribedRecordNotExists($customer);
         $this->assertCurrentCustomerCacheRecordExists($customer);
 
-        // query customer again so that subscription record
+        // query customer again so that subscription cache record is created
         $response = $this->graphQlQueryWithResponseHeaders(
             $query,
             [],