Amplify updates lambda CFN templates on each push

When creating lambda functions through `amplify function add` amplify creates CloudFormation template. This template is meant to be stored in the git repository (because it describes lambda and can have manual changes). The problem is that on each `amplify push` this file is modified with the following lines:
```
"Code": {
"S3Bucket": "",
"S3Key": ""
}
```

Later you need to either manually rollback files in git or resolve merge conflicts for those lines which makes no sense.

I propose to not update those files and perform all generation in the temp files