ci: fine-tune the rpm repos paths for centos-stream8 builds

build/ci/platforms/centos-stream8-container.yml

@@ -9,7 +9,7 @@ container:
     FROM quay.io/centos/centos:stream8
     RUN sed -i -e '/mirrorlist=/d' /etc/yum.repos.d/CentOS-*.repo
     RUN sed -i -e 's/#baseurl=/baseurl=/g' /etc/yum.repos.d/CentOS-*.repo
-    RUN sed -i -e 's,http://mirror.centos.org/centos/,https://vault.centos.org/,g' /etc/yum.repos.d/CentOS-*.repo
+    RUN sed -i -e 's,http://mirror.centos.org/,https://vault.centos.org/,g' /etc/yum.repos.d/CentOS-*.repo
     RUN dnf install -y sudo glibc-langpack-en
     RUN dnf install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
     RUN useradd --create-home pcpbuild