Improve Dockerfile apk cache handling

[PeterDaveHello]

Drop the redundant apk update and cache removal commands in the runtime stage. The --no-cache flag already keeps the package index out of the layer, so the simplified instruction avoids needless work.

GitHub Copilot Summary:

This pull request makes a minor change to the Dockerfile by simplifying the package installation step. The unnecessary cache clearing and update command have been removed, streamlining the build process.

[snshn]

Thank you.