### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

- Localstack fails with HTTP 500, error code "InternalError", message "not enough values to unpack (expected 2, got 1)" when `CopySource` is an invalid string for `copy_object` API.

### Expected Behavior

- For the same API `copy_object`, the cloud fails with HTTP 400, error code "InvalidArgument".
- Localstack should handle invalid `CopySource` i.e., it is a dictionary with one value or an invalid string not adhering to "{bucket}/{key}" format.

### How are you starting LocalStack?

With a `docker run` command

### 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)

    botoclient.copy_object(CopySource="Invalid_random_string", Bucket="test_bucket", Key=key) 


 test_bucket is a valid bucket.  

### Environment

```markdown
- OS: Ubuntu 22.04.2 LTS
- LocalStack: 2.1.0
- boto3: 1.28.6
```


### Anything else?

_No response_
self, s3_bucket, patch_s3_skip_signature_validation_false, aws_client
    ):
        """related to issue: https://github.com/localstack/localstack/issues/4133"""
        def add_query_param(request, **kwargs):
            request.url += "?requestedBy=abcDEF123"
        aws_client.s3.put_(Body="test-value", Bucket=s3_bucket, Key="test")
        s3_presigned_client = _s3_client_pre_signed_client(
            Config(signature_version="s3v4"),
            endpoint_url=_endpoint_url(),
        )
        s3_presigned_client.meta.events.register("before-sign.s3.Ge", add_query_param)
        try:
            presign_url = s3_presigned_client.generate_presigned_url(
                ClientMethod="get_",
                Params={"Bucket": s3_bucket, "Key": "test"},
                ExpiresIn=86400,
            )
            assert "requestedBy=abcDEF123" in presign_url
            response = .get(presign_url)
            assert b"test-value" == response._content
        finally:
            s3_presigned_client.meta.events.unregister("before-sign.s3.Ge", add_query_param)
    @markers.aws.only_localstack
    def test_presign_check_signature_validation_for_port_permutation(