Roll back test change

Author: julian-elastic

x-pack/plugin/esql/qa/testFixtures/src/main/resources/lookup-join-expression.csv-spec

@@ -735,26 +735,3 @@ id_int:integer | name_str:keyword | extra1:keyword | other1:keyword | other2:int
 13             | Mia              | thud           | xi             | 14000
 14             | Nina             | foo2           | omicron        | 15000
 ;
-
-
-lookupJoinExpressionOnUnionTypes
-required_capability: join_lookup_v12
-required_capability: lookup_join_on_boolean_expression
-required_capability: metadata_fields_remote_test
-
-FROM apps, apps_short METADATA _index
-| EVAL language_code = id::integer
-| KEEP _index, language_code
-| WHERE language_code < 3
-| RENAME language_code as language_code_left
-| LOOKUP JOIN languages_lookup ON language_code_left == language_code
-| KEEP _index, language_code, language_name
-| SORT _index ASC, language_code ASC
-;
-
-_index:keyword            | language_code:integer | language_name:keyword
-remote_cluster:apps       | 1                     | English
-remote_cluster:apps       | 2                     | French
-remote_cluster:apps_short | 1                     | English
-remote_cluster:apps_short | 2                     | French
-;