tests: cache: Invoke partial eviction in test_concurrent_reads_and_eviction
tests: cache: Invoke partial eviction in test_concurrent_reads_and_eviction

In hope of catching more issues.

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