Tests: Fix failure introduced in #8967

src/test/java/org/elasticsearch/index/mapper/update/default_mapping_with_disabled_root_types.json

@@ -1 +1 @@
-{"type":{"_timestamp":{"enabled":false,"fielddata":{"format":"doc_values"}},"_index":{"store":true,"enabled":false,"fielddata":{"format":"fst"}},"_size":{"enabled":false},"properties":{}}}
+{"type":{"_timestamp":{"enabled":false,"doc_values":true,"fielddata":{"format":"doc_values"}},"_index":{"store":true,"enabled":false,"fielddata":{"format":"fst"}},"_size":{"enabled":false},"properties":{}}}