sdcm.cluster: Use shorter titles for graphs
sdcm.cluster: Use shorter titles for graphs

Use shorter descriptions for c-s generated graphs, to
keep things simple and to the point.

Signed-off-by: Lucas Meneghel Rodrigues <8ad3460456640ab580599f5440c5a8d925a620b9@scylladb.com>

scylladb/scylla-cluster-tests,amoskong/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,amoskong/scylla-cluster-tests,amoskong/scylla-cluster-tests,scylladb/scylla-longevity-tests,amoskong/scylla-cluster-tests,scylladb/scylla-cluster-tests,amoskong/scylla-cluster-tests