centos/8/daemon: rename powertools repository

Starting with CentOS 8.3, the powertools repository has been renamed from
PowerTools to powertools.

Signed-off-by: Dimitri Savineau <dsavinea@redhat.com>
(cherry picked from commit b6c65fa)

ceph-releases/ALL/centos/8/daemon/__DOCKERFILE_INSTALL__

@@ -1,6 +1,6 @@
 echo 'Install packages' && \
       yum install -y wget unzip util-linux python3-setuptools udev device-mapper && \
-      yum install -y --enablerepo=PowerTools __DAEMON_PACKAGES__ && \
+      yum install -y --enablerepo=powertools __DAEMON_PACKAGES__ && \
     # Centos 8 doesn't have confd/forego/etcdctl/kubectl packages, so install them from web
     __WEB_INSTALL_CONFD__ && \
     __WEB_INSTALL_ETCDCTL__ && \