### 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_
import base64
import json
import os
import re
import shutil
import time
import unittest
from datetime import datetime
from io import BytesIO
import pytest
import requests
from botocore.exceptions import ClientError
from localstack import config
from localstack.constants import (