fix(grafana_snapsho): fix dom selector for monitoring 3.5
fix(grafana_snapsho): fix dom selector for monitoring 3.5

upgrade to scylla monitoring 3.5 bring new grafana version
and gui changes on pages.
- Updated the css selector to find the correct path to get snapshot
- Added ability to set css selector per page for taking snapshot

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