Consider removing support to java8 runtime

[rapphil]

Describe the bug
Java8 support is reaching end of the life. No new function can be created with the Java8 runtime.
https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html#runtimes-deprecated

Steps to reproduce
Try to create a new function that uses java8.

What did you expect to see?
That opentelemetry-lambda did not support java8.

What did you see instead?
Java8 is still supported.

Additional context
It is ok to deprecate java8 in my opinion because we still will support java8.al2.
https://aws.amazon.com/blogs/compute/announcing-migration-of-the-java-8-runtime-in-aws-lambda-to-amazon-corretto/

[tylerbenson]

Sounds reasonable to me.

[knarfli]

I want to take a look into it.

[rapphil]

@knarfli feel free to take a look into it. It should be a simple change in our release scripts. Thanks for the interest.

[knarfli]

Thanks @rapphil , I am working on that and will create a PR.

[serkan-ozal]

I agree on this too. I think, we will just remove java8 from supported runtimes in the layer, right? Is there anything to do?

[tylerbenson]

I think that's all that's required.

[knarfli]

yes, agree with that, I have raised a pull request in a forked repository, but I need to follow some steps which block making the pull request here, let me try to speed it up.

[knarfli]

Pull request opened, #1481.
Please review.