ci: use Alpine Linux Docker image

[jpnurmi]

Reverts most of the Alpine-specific steps introduced in #1233 by using a prebuilt Alpine Linux Docker image with relevant tools and dependencies pre-installed:

• https://github.com/getsentry/sentry-native/pkgs/container/sentry-native-alpine

Close: #1240

#skip-changelog

[supervacuus]

Note: Once everything looks good, the first commit needs to be cherry-picked into a separate PR, merged first, and run once to make the Docker image available at getsentry/packages. Until then, the image is temporarily published from a personal fork.

Can't you just manually dispatch the docker workflow from the PR branch and then rerun the CI workflow?

[jpnurmi]

Can't you just manually dispatch the docker workflow from the PR branch and then rerun the CI workflow?

For security reasons, the workflow must exist in the default branch to be able to trigger workflow_dispatch but it made me wonder if workflow_call from the PR branch is allowed...

[jpnurmi]

Thanks, seems like it worked so we don't need multiple steps... 🎉

https://github.com/getsentry/sentry-native/pkgs/container/sentry-native-alpine

[supervacuus]

This looks good, but I would like to have an idea of the updates to the image. Your primary concern will be updates to the Alpine base, but even minor changes (such as filtering on branches) could make this significantly safer.