Fix nodemgr cassandra detection

The nodemgr uses `Dcassandra-pidfile=.*cassandra\.pid` to detect
PID of running cassandra, so we need to add this parameter to
cassandra-env.sh.

PROD-17158
PROD-16393

Change-Id: Ifb163421bdb0734b2677935f5296d363a5113541
2 files changed