Fix compilation after #120045

#120045 was merged in between the work for #120096.
As a result the compilation is broken.

Author: jimczi

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/mapper/SemanticInferenceMetadataFieldsRecoveryTests.java

@@ -77,7 +77,7 @@ protected Settings indexSettings() {
             .put(super.indexSettings())
             .put(InferenceMetadataFieldsMapper.USE_LEGACY_SEMANTIC_TEXT_FORMAT.getKey(), false);
         if (useSynthetic) {
-            builder.put(SourceFieldMapper.INDEX_MAPPER_SOURCE_MODE_SETTING.getKey(), SourceFieldMapper.Mode.SYNTHETIC.name());
+            builder.put(IndexSettings.INDEX_MAPPER_SOURCE_MODE_SETTING.getKey(), SourceFieldMapper.Mode.SYNTHETIC.name());
             builder.put(IndexSettings.RECOVERY_USE_SYNTHETIC_SOURCE_SETTING.getKey(), true);
         }
         return builder.build();