Re-add #from_query test case for anonymouse query

- https://gitlab.com/gitlab-org/gitlab/-/merge_requests/83281#note_884469872

spec/lib/gitlab/graphql/known_operations_spec.rb

@@ -19,6 +19,7 @@ RSpec.describe Gitlab::Graphql::KnownOperations do
 
   describe "#from_query" do
     where(:query_string, :expected) do
+      "query { helloWorld }"         | described_class::UNKNOWN
       "query fuzzyyy { helloWorld }" | described_class::UNKNOWN
       "query foo { helloWorld }"     | described_class::Operation.new("foo")
     end