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"
```
from pympler import muppy, summary
        all_objects = muppy.get_objects()
        result = summary.summarize(all_objects)
        result = result[0:20]
        summary = '\n'.join([l for l in summary.format_(result)])
        result = '%s\n\n%s' % (summary, json.dumps(result))
        return result, 200, {'content-type': 'text/plain'}
    def create_backend_app(service):
        backend_app = moto_server.create_backend_app_orig(service)
        backend_app.add_url_rule(
            '/_stats', endpoint='_get_stats', methods=['GET'], view_func=_get_stats, strict_slashes=False)
        return backend_app
    if not hasattr(moto_server, 'create_backend_app_orig'):
        moto_server.create_backend_app_orig = moto_server.create_backend_app
        moto_server.create_backend_app = create_backend_app
def start_up(*args):
    
    apply_patches()
    
    inject_stats_endpoint()
    return moto_main(*args)
def main():
    setup_logging()
    
    canonicalize_api_names()
    
    sys.exit(start_up())
if __name__ == '__main__':
    main()