Change busybox variant to musl (#4608)

Author: lucacome

build/Dockerfile

@@ -69,7 +69,7 @@ ADD --link --chown=101:0 https://raw.githubusercontent.com/nginxinc/k8s-common/m
 ADD --link --chown=101:0 https://raw.githubusercontent.com/nginxinc/k8s-common/main/files/nap-waf-debian-11.repo nap-waf-11.sources
 ADD --link --chown=101:0 https://raw.githubusercontent.com/nginxinc/k8s-common/main/files/nap-dos-debian-11.repo nap-dos-11.sources
 
-RUN --mount=from=busybox:uclibc,src=/bin/,dst=/bin/ printf "%s\n" "Acquire::https::pkgs.nginx.com::User-Agent \"k8s-ic-$IC_VERSION${BUILD_OS##debian-plus}-apt\";" >> 90pkgs-nginx \
+RUN --mount=from=busybox:musl,src=/bin/,dst=/bin/ printf "%s\n" "Acquire::https::pkgs.nginx.com::User-Agent \"k8s-ic-$IC_VERSION${BUILD_OS##debian-plus}-apt\";" >> 90pkgs-nginx \
 	&& sed -i -e "s;%VERSION%;${NGINX_PLUS_VERSION};g" *.sources \
 	&& sed -i -e "y/0/1/" -e "1,8s;/centos;/${NGINX_PLUS_VERSION}/centos;" *.repo