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
if (painlessConstructor == null) {
            return null;
        }
        return painlessConstructor;
    }
    public PainlessMethod lookupPainlessMethod(String targetCanonicalClassName, boolean isStatic, String methodName, int methodArity) {
        Objects.requireNonNull(targetCanonicalClassName);
        Class<?> targetClass = canonicalTypeNameToType(targetCanonicalClassName);
        if (targetClass == null) {
            return null;
        }
        return lookupPainlessMethod(targetClass, isStatic, methodName, methodArity);
    }
    public PainlessMethod lookupPainlessMethod(Class<?> targetClass, boolean isStatic, String methodName, int methodArity) {
        Objects.requireNonNull(targetClass);
        Objects.requireNonNull(methodName);
        if (classesToPainlessClasses.containsKey(targetClass) == false) {
            return null;
        }
        if (targetClass.isPrimitive()) {
            targetClass = typeToBoxedType(targetClass);
            if (classesToPainlessClasses.containsKey(targetClass) == false) {
                return null;
            }
        }
        String painlessMethodKey = buildPainlessMethodKey(methodName, methodArity);
        Function<PainlessClass, PainlessMethod> objectLookup = isStatic
            ? targetPainlessClass -> targetPainlessClass.staticMethods.get(painlessMethodKey)
            : targetPainlessClass -> targetPainlessClass.methods.get(painlessMethodKey);
        return lookupPainlessObject(targetClass, objectLookup);