tests: perf_cache_eviction: Switch to time-series like workload
tests: perf_cache_eviction: Switch to time-series like workload

Before the patch we appended and queried at the front. Insert at the
front instead, so that writes and reads overlap. Stresses eviction and
population more.
Message-Id: <6f4ab370216be70021404a10992c8e31714bc44e@scylladb.com>

avikivity/scylla,scylladb/scylla,duarten/scylla,scylladb/scylla,avikivity/scylla,duarten/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla