btrfs-progs: ci: fix Centos 8 package urls

A fresh build of Centos 8 fails due to changes in upstream repositoris:

"Error: Failed to download metadata for repo ‘appstream’: Cannot prepare
internal mirrorlist: No URLs in mirrorlist"

There are repositories no longer updated (and missing some packages like
reiserfs-utils) but for our CI purposes it's sufficient so make it work.

Signed-off-by: David Sterba <dsterba@suse.com>

ci/images/ci-centos-8-x86_64/Dockerfile

@@ -3,12 +3,15 @@ FROM centos:8
 WORKDIR /tmp
 
 RUN rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
+# Errors due to missing mirrors since 01/2022
+RUN sed -i -e "s|mirrorlist=|#mirrorlist=|" /etc/yum.repos.d/CentOS-*
+RUN sed -i -e "s|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|" /etc/yum.repos.d/CentOS-*
 RUN yum -y install https://www.elrepo.org/elrepo-release-8.el8.elrepo.noarch.rpm
 RUN yum -y install epel-release
 
 RUN yum -y install autoconf automake pkg-config
 RUN yum -y install libattr-devel libblkid-devel libuuid-devel
-RUN yum -y install e2fsprogs-libs e2fsprogs-devel reiserfs-utils
+RUN yum -y install e2fsprogs-libs e2fsprogs-devel
 RUN yum -y install zlib-devel lzo-devel libzstd-devel zstd
 RUN yum -y install make gcc tar gzip clang
 RUN yum -y install python3 python3-devel python3-setuptools