When trying to deploy a serverless service that does not currently deploy correctly onto localstack using a custom deployment bucket, the lambdas seems to be created regardless (???) but not as part of the stack, with localstack outputting `botocore.errorfactory.ResourceConflictException: An error occurred (ResourceConflictException) when calling the CreateFunction operation: Function already exist` .

For example, the `serverless.yml` below would currently fail to deploy due to  #1676 , but because a `deploymentBucket` was added, it will instead fail due to `Function already exist`. Subsequently removing `deploymentBucket` or even `events` from the the file will not allow it to deploy - it will fail until localstack is restarted ( or until the lambda is manually deleted?).

I've also reproduced this with services suffering from #1675. 

```yaml
service: "localtest"

provider:
  name: "aws"
  runtime: "nodejs10.x"
  deploymentBucket:
    name: "testbucket"

functions:
  hello:
    handler: "handler.hello"
    events:
      - schedule: "cron(0 * * * ? *)"

plugins:
- "serverless-localstack"

custom:
  localstack:
    stages:
      - "local"
```
props = cloudformation_json['Properties']
        name = props['StageName']
        deployment_id = props.get('Id') or short_uid()
        description = props.get('Description') or ''
        return apigw_models.Deployment(deployment_id, name, description)
    @classmethod
    def Resource_create_from_cloudformation_json(cls, resource_name, cloudformation_json, region_name):
        props = cloudformation_json['Properties']
        region_name = props.get('Region') or aws_stack.get_region()
        path_part = props.get('PathPart')
        api_id = props.get('RestApiId')
        parent_id = props.get('ParentId')
        id = props.get('Id') or short_uid()
        return apigw_models.Resource(id, region_name, api_id, path_part, parent_id)
    @classmethod
    def Method_create_from_cloudformation_json(cls, resource_name, cloudformation_json, region_name):
        props = cloudformation_json['Properties']
        method_type = props.get('HttpMethod')
        authorization_type = props.get('AuthorizationType')
        return apigw_models.Method(method_type, authorization_type)
    apigw_models.RestAPI.create_from_cloudformation_json = RestAPI_create_from_cloudformation_json
    apigw_models.RestAPI.get_cfn_attribute = RestAPI_get_cfn_attribute
    apigw_models.Deployment.create_from_cloudformation_json = Deployment_create_from_cloudformation_json
    apigw_models.Resource.create_from_cloudformation_json = Resource_create_from_cloudformation_json
    apigw_models.Method.create_from_cloudformation_json = Method_create_from_cloudformation_json
    
    
    def describe_stack_resource(self):