Adapt to upstream changes

Possilby after #61457, the priority we use for the index template that converts core yaml tests to use runtime fields is already taken, which causes an error as there ma be multiple matching templates with same priority.

Author: javanna

x-pack/plugin/runtime-fields/qa/rest/src/yamlRestTest/java/org/elasticsearch/xpack/runtimefields/rest/CoreTestsWithRuntimeFieldsIT.java

@@ -239,7 +239,7 @@ public void execute(ClientYamlTestExecutionContext executionContext) throws IOEx
             List<Map<String, Object>> bodies = List.of(
                 Map.ofEntries(
                     Map.entry("index_patterns", "*"),
-                    Map.entry("priority", Integer.MAX_VALUE),
+                    Map.entry("priority", Integer.MAX_VALUE - 1),
                     Map.entry("template", Map.of("settings", Map.of(), "mappings", Map.of("dynamic_templates", dynamicTemplates)))
                 )
             );