github-action: avoid release if github release already exists

[v1v]

What

If a github release exists, then it fails. Avoid rerunning the workflow since AWS lambdas are immutable and their versions are bumped if created a new one.

Why

This should avoid the edge case that a GitHub workflow was triggered accidentally and remove the lambdas.

Test

Further details

github.ref_name string The short ref name of the branch or tag that triggered the workflow run. This value matches the branch or tag name shown on GitHub. For example, feature-branch-1.
For pull requests, the format is <pr_number>/merge.

[reakaleek]

Should we also remove https://github.com/elastic/apm-aws-lambda/blob/main/.ci/publish-aws.sh#L29-L40?

[dmathieu]

Won't the tag always already exist, since this action is triggered by its creation?

[v1v]

Won't the tag always already exist, since this action is triggered by its creation?

😄 ... did I took the wrong approach here?

I'll use the release validation instead