Test that alpine bindists are not static

Following https://gitlab.haskell.org/ghc/ghc/-/issues/23043 I have decided that GHCup will not distribute static alpine bindists anymore in the default release channel.

CI will be enhanced to catch that.

Instead, static alpine will only be provided through a separate release channel: https://github.com/haskell/ghcup-metadata/issues/91

@mpickering @bgamari

Start by reviewing the repository's CI configuration and the metadata paths that produce Alpine bindists. Add coverage showing that static Alpine bindists are rejected from the default release channel, while the separate release channel remains available; the CI run should catch a static default-channel bindist.

Written by the indexing model from the issue text.