Modify systemd env file to be in sync with opensearch-build

Signed-off-by: Rajat Gupta <gptrajat@amazon.com>

Author: Rajat Gupta

distribution/packages/src/common/env/opensearch

@@ -3,17 +3,17 @@
 ################################
 
 # OpenSearch home directory
-#OPENSEARCH_HOME=/usr/share/opensearch
+OPENSEARCH_HOME=/usr/share/opensearch
 
 # OpenSearch Java path
-#OPENSEARCH_JAVA_HOME=
+#OPENSEARCH_JAVA_HOME=/usr/lib/jvm/java-11-amazon-corretto
 
 # OpenSearch configuration directory
 # Note: this setting will be shared with command-line tools
-OPENSEARCH_PATH_CONF=${path.conf}
+OPENSEARCH_PATH_CONF=/etc/opensearch
 
 # OpenSearch PID directory
-#PID_DIR=/var/run/opensearch
+PID_DIR=/var/run/opensearch
 
 # Additional Java OPTS
 #OPENSEARCH_JAVA_OPTS=
@@ -25,11 +25,12 @@ OPENSEARCH_PATH_CONF=${path.conf}
 # OpenSearch service
 ################################
 
-# SysV init.d
-#
 # The number of seconds to wait before checking if OpenSearch started successfully as a daemon process
 OPENSEARCH_STARTUP_SLEEP_TIME=5
 
+# Notification for systemd
+OPENSEARCH_SD_NOTIFY=true
+
 ################################
 # System properties
 ################################
@@ -49,4 +50,4 @@ OPENSEARCH_STARTUP_SLEEP_TIME=5
 # Maximum number of VMA (Virtual Memory Areas) a process can own
 # When using Systemd, this setting is ignored and the 'vm.max_map_count'
 # property is set at boot time in /usr/lib/sysctl.d/opensearch.conf
-#MAX_MAP_COUNT=262144
+#MAX_MAP_COUNT=262144