Upload only plugin archives as latest plugins

[mszostok]

Description

Changes proposed in this pull request:

For the latest plugin release, we use only archive plugins on index.yaml. However, we still push both the binaries and archives making the bucket size to grow.

• Upload only plugin archives as latest plugins

Testing

Tested on CI branch: https://github.com/kubeshop/botkube/actions/runs/6455472645/job/17523021491?pr=1287

 ▲ gsutil du -s -h gs://botkube-plugins-latest                                                                                                            2s
1.38 GiB     gs://botkube-plugins-latest

 ▲ gsutil du -s -h "gs://botkube-plugins-latest/*.tar.gz"
685.12 MiB   gs://botkube-plugins-latest/*.tar.gz

 ▲ gsutil du -s -h -e "*.tar.gz" gs://botkube-plugins-latest/                                                                                             2s
723.15 MiB   gs://botkube-plugins-latest

Before merge I will clean the whole bucket so binaries will be removed and latest main will push only archives.