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"
```
if hasattr(entity, 'physical_resource_id'):
        return entity.physical_resource_id
    
    types_with_ref_as_id_or_name = (apigw_models.RestAPI, apigw_models.Resource)
    attr_candidates = ['function_arn', 'Arn', 'Ref', 'id', 'Id', 'name', 'Name']
    for attr in attr_candidates:
        if hasattr(entity, attr):
            if attr in ['id', 'name'] and not isinstance(entity, types_with_ref_as_id_or_name):
                LOG.warning('Unable to find ARN, using "%s" instead: %s - %s',
                            attr, resource_json, entity)
            return getattr(entity, attr)
        if hasattr(entity, 'get_cfn_attribute'):
            try:
                result = entity.get_cfn_attribute(attr)
                if result:
                    return result
            except Exception:
                pass
    
    if hasattr(entity, 'params'):
        for key, value in (entity.params or {}).items():
            if key.endswith('Name'):
                return value
def convert_objs_to_ids(resource_json):