Switch to xx-cargo (#6640)

- removes a lot of additional configuration lines from the Dockerfile
- includes the workaround for the `openssl-sys` build issues with improper `pkg-config` setup
- for reference: https://github.com/tonistiigi/xx/pull/108#issuecomment-3700635977

docker/Dockerfile.alpine

@@ -57,7 +57,6 @@ ENV DEBIAN_FRONTEND=noninteractive \
     # Debian Trixie uses libpq v17
     PQ_LIB_DIR="/usr/local/musl/pq17/lib"
 
-
 # Create CARGO_HOME folder and don't download rust docs
 RUN mkdir -pv "${CARGO_HOME}" && \
     rustup set profile minimal