### 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_
INSTALL_DIR_INFRA = os.path.join(MODULE_MAIN_PATH, "infra")
LOCALSTACK_VENV_FOLDER = os.path.join(LOCALSTACK_ROOT_FOLDER, ".venv")
if not os.path.isdir(LOCALSTACK_VENV_FOLDER):
    
    LOCALSTACK_VENV_FOLDER = os.path.realpath(
        os.path.join(LOCALSTACK_ROOT_FOLDER, "..", "..", "..")
    )
PATH_USER_REQUEST = "_user_request_"
DOCKER_IMAGE_NAME = "localstack/localstack"
DOCKER_IMAGE_NAME_FULL = "localstack/localstack-full"
CONFIG_UPDATE_PATH = "/?_config_"
ENV_INTERNAL_TEST_RUN = "LOCALSTACK_INTERNAL_TEST_RUN"
ENV_PRO_ACTIVATED = "PRO_ACTIVATED"
HEADER_CONTENT_TYPE = "Content-Type"
APPLICATION_AMZ_JSON_1_0 = "application/x-amz-json-1.0"
APPLICATION_AMZ_JSON_1_1 = "application/x-amz-json-1.1"
APPLICATION_AMZ_CBOR_1_1 = "application/x-amz-cbor-1.1"
APPLICATION_CBOR = "application/cbor"
APPLICATION_JSON = "application/json"
APPLICATION_XML = "application/xml"
APPLICATION_OCTET_STREAM = "application/octet-stream"
APPLICATION_X_WWW_FORM_URLENCODED = "application/x-www-form-urlencoded"
TRUE_STRINGS = ("1", "true", "True")
FALSE_STRINGS = ("0", "false", "False")
LOG_LEVELS = ("trace-internal", "trace", "debug", "info", "warn", "error", "warning")
LAMBDA_TEST_ROLE = "arn:aws:iam::%s:role/lambda-test-role" % TEST_AWS_ACCOUNT_ID
ELASTICSEARCH_URLS = {
    "7.10.0": "https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.10.0-linux-x86_64.tar.gz",
    "7.7.0": "https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.7.0-linux-x86_64.tar.gz",
    "7.4.0": "https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.4.0-linux-x86_64.tar.gz",