### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

Up to localstack 0.12.15 (I haven't checked with 0.12.16), Java 11 Lambda function handler was correctly specified according to [AWS docs](https://docs.aws.amazon.com/lambda/latest/dg/lambda-java.html) e.g.

```
example.Hello::handleRequest
```

With 0.12.17, instead, such specification leads to error during Lambda execution, with stacktrace:

```
2021-08-30T14:08:01:INFO:localstack.utils.run: Thread run method <function LambdaExecutor.execute.<locals>.do_execute at 0x7fc385d26560>(None) failed: Lambda process returned error status code: 1. Result: . Output:
Exception in thread "main" java.lang.ClassNotFoundException: example.Hello::handleRequest
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(Unknown Source)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(Unknown Source)
        at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
        at java.base/java.lang.Class.forName0(Native Method)
        at java.base/java.lang.Class.forName(Unknown Source)
        at cloud.localstack.LambdaExecutor.getHandler(LambdaExecutor.java:142)
        at cloud.localstack.LambdaExecutor.main(LambdaExecutor.java:69) Traceback (most recent call last):
  File "/opt/code/localstack/localstack/utils/run.py", line 138, in run
    result = self.func(self.params, **kwargs)
  File "/opt/code/localstack/localstack/services/awslambda/lambda_executors.py", line 326, in do_execute
    return _run(func_arn=func_arn)
  File "/opt/code/localstack/localstack/utils/cloudwatch/cloudwatch_util.py", line 157, in wrapped
    raise e
  File "/opt/code/localstack/localstack/utils/cloudwatch/cloudwatch_util.py", line 153, in wrapped
    result = func(*args, **kwargs)
  File "/opt/code/localstack/localstack/services/awslambda/lambda_executors.py", line 313, in _run
    raise e
  File "/opt/code/localstack/localstack/services/awslambda/lambda_executors.py", line 299, in _run
    result = self._execute(func_arn, func_details, event, context, version)
  File "/opt/code/localstack/localstack/services/awslambda/lambda_executors.py", line 1101, in _execute
    raise InvocationException(result, log_output)
localstack.services.awslambda.lambda_executors.InvocationException: Lambda process returned error status code: 1. Result: . Output:
Exception in thread "main" java.lang.ClassNotFoundException: example.Hello::handleRequest
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(Unknown Source)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(Unknown Source)
        at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
        at java.base/java.lang.Class.forName0(Native Method)
        at java.base/java.lang.Class.forName(Unknown Source)
        at cloud.localstack.LambdaExecutor.getHandler(LambdaExecutor.java:142)
        at cloud.localstack.LambdaExecutor.main(LambdaExecutor.java:69)
```

I would say that this line in the test case is incorrect: https://github.com/localstack/localstack/blob/master/tests/integration/test_lambda.py#L1711

### Expected Behavior

I would expect to specify Java 11 Lambda handlers as it used to be at least until localstack 0.12.15 and according to AWS docs.

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    docker run localstack/localstack

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

    awslocal s3 mb s3://mybucket


### Environment

```markdown
- OS: Ubuntu 20.04
- LocalStack: 0.12.17
```


### Anything else?

_No response_
events_before = run_safe(get_lambda_log_events, function_name, regex_filter="Records") or []
        s3_client.put_object(Bucket=bucket_name, Key=key, Body="something")
        time.sleep(2)
        
        retry(
            function=check_expected_lambda_log_events_length,
            retries=3,
            sleep=1,
            expected_length=len(events_before) + 1,
            function_name=function_name,
            regex_filter="Records",
        )
        
        sns_client.delete_topic(TopicArn=topic_arn)
        s3_client.delete_objects(Bucket=bucket_name, Delete={"Objects": [{"Key": key}]})
        s3_client.delete_bucket(Bucket=bucket_name)
def test_java_custom_handler_method_specification(lambda_client, create_lambda_function):
    java_handler_multiple_handlers = load_file(TEST_LAMBDA_JAVA_MULTIPLE_HANDLERS, mode="rb")
    expected = ['.*"echo": "echo".*']
    function_name_custom_handler = "lambda_custom_handler_%s" % short_uid()
    create_lambda_function(
        func_name=function_name_custom_handler,
        zip_file=java_handler_multiple_handlers,
        runtime=LAMBDA_RUNTIME_JAVA11,
        handler="cloud.localstack.sample.LambdaHandlerWithInterfaceAndCustom::handleRequestCustom",
    )
    result = lambda_client.invoke(
        FunctionName=function_name_custom_handler, Payload=b'{"echo":"echo"}'
    )
    result_data = result["Payload"].read()