### 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_
# auth 
        new_query_params = {"x-amz-request-payer": ["non-valid"]}
        for k, v in query_params.items():
            new_query_params[k] = v[0]
        new_query_params = urlencode(new_query_params, quote_via=quote, safe=" ")
        new_url = urlunsplit(
            SplitResult(  # noqa
                parsed.scheme, parsed.netloc, parsed.path, new_query_params, parsed.fragment
            )
        )
        response = .put(
            new_url,
            data="test_data",
            headers={"x-amz-request-payer": "requester"},
        )
        exception = xmltodict.parse(response.content) if response.content else {}
        exception["StatusCode"] = response.status_code
        snapshot.match("double-header-query-string", exception)
        # test 
        response = .put(
            presigned_url,
            data="test_data",
            headers={"x-amz-expires": "5"},
        )
        exception = xmltodict.parse(response.content) if response.content else {}
        exception["StatusCode"] = response.status_code
        snapshot.match("override-signed-qs", exception)
    @markers.aws.validated
    @pytest.mark.parametrize("signature_version", ["s3", "s3v4"])
    def test_s3_put_presigned_url_missing_sig_param(