Don't install alja-xrootd into atlas-xcache (SOFTWARE-5998)

Author: matyasselmeci

Dockerfile

@@ -78,6 +78,7 @@ ARG BASE_YUM_REPO=testing
 ENV XC_IMAGE_NAME atlas-xcache
 
 RUN yum install -y --enablerepo=osg-contrib \
+        --exclude=alja-\* \
         atlas-xcache && \
     yum install -y python3 python3-psutil python3-requests && \
     yum clean all --enablerepo=* && rm -rf /var/cache/