Fix test for index phrases shortcut with multi-term synonyms (#49366)

Lucene 8.3 included a root fix for #43976, which was temporarily fixed in elasticsearch
by #44340. Since we have upgraded to 8.3 we no longer need this workaround. This
commit fixes the test that was added to check the workaround, and instead checks that
fields with index_phrases enabled correctly build queries when used with multi-term
synonyms.

Closes #47777

server/src/test/java/org/elasticsearch/index/mapper/TextFieldMapperTests.java

@@ -771,7 +771,6 @@ public void testNestedIndexPrefixes() throws IOException {
         }
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/47777")
     public void testFastPhraseMapping() throws IOException {
 
         QueryShardContext queryShardContext = indexService.newQueryShardContext(
@@ -841,8 +840,7 @@ protected TokenStreamComponents createComponents(String fieldName) {
         assertThat(q7, is(new BooleanQuery.Builder().add(new BooleanQuery.Builder()
             .add(new TermQuery(new Term("synfield", "foo")), BooleanClause.Occur.SHOULD)
             .add(new PhraseQuery.Builder()
-                .add(new Term("synfield", "bar"))
-                .add(new Term("synfield", "baz"))
+                .add(new Term("synfield._index_phrase", "bar baz"))
                 .build(), BooleanClause.Occur.SHOULD)
             .build(), BooleanClause.Occur.SHOULD).build()));