image: revert to before installing rust

it seems like github wants a specific user config setup, too much work to do the same day of the release

Dockerfile

@@ -11,23 +11,3 @@ WORKDIR /tmp/gtk-4.6.0
 RUN meson _build --prefix=/usr -Dgtk_doc=false -Dintrospection=disabled -Dbuild-examples=false -Dbuild-tests=false -Ddemos=false
 RUN ninja -C _build
 RUN ninja -C _build install
-
-# set up a user
-ARG HOST_USER_ID=5555
-ENV HOST_USER_ID ${HOST_USER_ID}
-RUN useradd -u $HOST_USER_ID -ms /bin/bash user
-
-USER user
-WORKDIR /home/user
-
-# install rust stable/nightly/beta/latest supported version
-
-RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- --default-toolchain none -y
-ENV PATH="/home/user/.cargo/bin:${PATH}"
-
-RUN rustup toolchain install stable --profile minimal --allow-downgrade -c clippy -c rustfmt
-RUN rustup toolchain install beta --profile minimal --allow-downgrade -c clippy -c rustfmt
-RUN rustup toolchain install nightly --profile minimal --allow-downgrade -c clippy -c rustfmt
-RUN rustup toolchain install 1.56.0 --profile minimal --allow-downgrade -c clippy -c rustfmt
-
-RUN rustup default stable