Remove useless capability.

Author: afoucret

x-pack/plugin/esql/qa/testFixtures/src/main/resources/text-embedding.csv-spec

@@ -71,7 +71,6 @@ text_embedding with multiple knn queries
 required_capability: text_embedding_function
 required_capability: dense_vector_field_type_released
 required_capability: knn_function_v5
-required_capability: fork_v9
 
 FROM dense_vector_text METADATA _score, _id
 | WHERE KNN(text_embedding_field, TEXT_EMBEDDING("be excellent to each other", "test_dense_inference")) OR KNN(text_embedding_field, TEXT_EMBEDDING("live long and prosper", "test_dense_inference"))