Java 21 [#96932](https://github.com/elastic/elasticsearch/pull/96932) (`-Druntime.java=21`) breaks `java.util.List` lookups in Painless scripts.

```
invalid foreach loop: method [java.util.List, iterator/0] not found
member method [java.util.List, add/1] not found
member method [java.util.List, asCollection/0] not found
member method [java.util.List, asList/0] not found
member method [java.util.List, isEmpty/0] not found
member method [java.util.List, size/0] not found
member method [java.util.List, stream/0] not found
```

`:modules:lang-painless:test` (57 failures): https://gradle-enterprise.elastic.co/s/dkpi5pcitruwy
`:modules:lang-painless:yamlRestTest` (6 failures) https://gradle-enterprise.elastic.co/s/rsf3522r44ilc

```
java -version
openjdk version "21-ea" 2023-09-19
OpenJDK Runtime Environment (build 21-ea+27-2343)
OpenJDK 64-Bit Server VM (build 21-ea+27-2343, mixed mode, sharing)
```

Refs: https://github.com/elastic/elasticsearch/issues/96997
modules/lang-painless/src/main/java/org/elasticsearch/painless/lookup/PainlessLookup.java
private final Map<String, Class<?>> javaClassNamesToClasses;
    private final Map<String, Class<?>> canonicalClassNamesToClasses;
    private final Map<Class<?>, PainlessClass> classesToPainlessClasses;
    private final Map<Class<?>, Set<Class<?>>> classesToDirectSubClasses;
    private final Map<String, PainlessMethod> painlessMethodKeysToImportedPainlessMethods;
    private final Map<String, PainlessClassBinding> painlessMethodKeysToPainlessClassBindings;
    private final Map<String, PainlessInstanceBinding> painlessMethodKeysToPainlessInstanceBindings;
    PainlessLookup(
        Map<String, Class<?>> javaClassNamesToClasses,