- When attempting to remove a created lambda permission with the new fix from https://github.com/localstack/localstack/issues/1260, throws up `SerializationError`

Code being called:

```
func deleteLambdaPermission(ctx context.Context, destinationLambdaARN, permissionStatementID string) (err error) {
	lambdaClient := services.LambdaClient()
	lambdaRemovePermissionInput := &lambda.RemovePermissionInput{
		FunctionName: aws.String(destinationLambdaARN),
		StatementId:  aws.String(permissionStatementID),
	}
	_, err = lambdaClient.RemovePermissionWithContext(ctx, lambdaRemovePermissionInput)

	return
}
```

Checking for error in tests shows the following

```
 Expected
        <*awserr.requestError | 0xc0004a2180>: {
            awsError: {
                code: "SerializationError",
                message: "failed to unmarshal response error",
                errs: [
                    {
                        awsError: {
                            code: "UnmarshalError",
                            message: "failed decoding error message",
                            errs: [
                                {
                                    msg: "invalid character '<' looking for beginning of value",
                                    Offset: 1,
                                },
                            ],
                        },
                        bytes: [60, 33, 68, 79, 67, 84, 89, 80, 69, 32, 72, 84, 77, 76, 32, 80, 85, 66, 76, 73, 67, 32, 34, 45, 47, 47, 87, 51, 67, 47, 47, 68, 84, 68, 32, 72, 84, 77, 76, 32, 51, 46, 50, 32, 70, 105, 110, 97, 108, 47, 47, 69, 78, 34, 62, 10, 60, 116, 105, 116, 108, 101, 62, 52, 48, 52, 32, 78, 111, 116, 32, 70, 111, 117, 110, 100, 60, 47, 116, 105, 116, 108, 101, 62, 10, 60, 104, 49, 62, 78, 111, 116, 32, 70, 111, 117, 110, 100, 60, 47, 104, 49, 62, 10, 60, 112, 62, 84, 104, 101, 32, 114, 101, 113, 117, 101, 115, 116, 101, 100, 32, 85, 82, 76, 32, 119, 97, 115, 32, 110, 111, 116, 32, 102, 111, 117, 110, 100, 32, 111, 110, 32, 116, 104, 101, 32, 115, 101, 114, 118, 101, 114, 46, 32, 73, 102, 32, 121, 111, 117, 32, 101, 110, 116, 101, 114, 101, 100, 32, 116, 104, 101, 32, 85, 82, 76, 32, 109, 97, 110, 117, 97, 108, 108, 121, 32, 112, 108, 101, 97, 115, 101, 32, 99, 104, 101, 99, 107, 32, 121, 111, 117, 114, 32, 115, 112, 101, 108, 108, 105, 110, 103, 32, 97, 110, 100, 32, 116, 114, 121, 32, 97, 103, 97, 105, 110, 46, 60, 47, 112, 62, 10],
                    },
                ],
            },
            statusCode: 404,
            requestID: "",
            bytes: nil,
        }
    to be nil
```
def test_invocation_type_event(self):
        result = self.lambda_client.invoke(
            FunctionName=TEST_LAMBDA_NAME_PY,
            Payload=b'{}', InvocationType='Event')
        self.assertEqual(result['StatusCode'], 202)
    def test_invocation_type_dry_run(self):
        result = self.lambda_client.invoke(
            FunctionName=TEST_LAMBDA_NAME_PY, Payload=b'{}',
            InvocationType='DryRun')
        self.assertEqual(result['StatusCode'], 204)
    def test_add_lambda_permission(self):
        iam_client = aws_stack.connect_to_service('iam')
        
        action = 'lambda:InvokeFunction'
        resp = self.lambda_client.add_permission(FunctionName=TEST_LAMBDA_NAME_PY, Action=action,
            StatementId='s3', Principal='s3.amazonaws.com', SourceArn=aws_stack.s3_bucket_arn('test-bucket'))
        self.assertIn('Statement', resp)
        
        policy = self.lambda_client.get_policy(FunctionName=TEST_LAMBDA_NAME_PY)['Policy']
        self.assertEqual(policy['Statement'][0]['Action'], action)
        self.assertEqual(policy['Statement'][0]['Resource'], lambda_api.func_arn(TEST_LAMBDA_NAME_PY))
        
        policies = iam_client.list_policies(Scope='Local', MaxItems=500)['Policies']
        matching = [p for p in policies if p['PolicyName'] == 'lambda_policy_%s' % TEST_LAMBDA_NAME_PY]
        self.assertEqual(len(matching), 1)
        self.assertIn(':policy/', matching[0]['Arn'])
    def test_lambda_environment(self):
        vars = {'Hello': 'World'}
        zip_file = testutil.create_lambda_archive(
            load_file(TEST_LAMBDA_ENV), get_content=True,