Skip publishing lambda layers for pre-releases

[andreiborza]

Description

We published an alpha release of the sentry-javascript SDKs earlier today and despite it being an alpha-release, the Lambda layer was published.

We brought this up previously in this issue but thought this function prevents publishing the layer:

https://github.com/getsentry/craft/blob/532b8d1950b351a4ca66f825ab906238a1cbf563/src/targets/awsLambdaLayer.ts#L196-L209

Upon further reflection, the function is just used to prevent publishing to our release-registry but it does not prevent publishing the layer to AWS.

Expected Result

Pre-releases not to publish our production AWS Lambda layers on AWS.

Actual Result

Pre-release published a new version of our AWS Lambda layer on AWS.