CI: Remove brctl from Arch Linux container

Package "bridge-utils" have been removed from the official repos, it
contained `brctl`. That utility is used by network hotplug scripts,
but they already check if it is available and switch to use "iproute2"
(`ip`) when not.

Signed-off-by: Anthony PERARD <anthony.perard@vates.tech>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

automation/build/archlinux/current.dockerfile

@@ -6,7 +6,6 @@ LABEL maintainer.name="The Xen Project" \
 RUN pacman-key --init
 
 RUN pacman -S --refresh --sysupgrade --noconfirm --noprogressbar --needed \
-        bridge-utils \
         bzip2 \
         cpio \
         discount \