Respect ES_PATH_CONF during upgrades too (elastic#50246)

A previous commit taught Elasticsearch packages to respect ES_PATH_CONF
during installs. Missed in that commit was respecting ES_PATH_CONF on
upgrades. This commit does that. Additionally, while ES_PATH_CONF is not
currently used in pre-install, this commit adds respect to the preinst
script in case we do in the future.

distribution/packages/src/common/scripts/posttrans

@@ -1,8 +1,15 @@
-if [ ! -f /etc/elasticsearch/elasticsearch.keystore ]; then
+# source the default env file
+if [ -f "${path.env}" ]; then
+    . "${path.env}"
+else
+  ES_PATH_CONF="${path.conf}"
+fi
+
+if [ ! -f "${ES_PATH_CONF}"/elasticsearch.keystore ]; then
     /usr/share/elasticsearch/bin/elasticsearch-keystore create
-    chown root:elasticsearch /etc/elasticsearch/elasticsearch.keystore
-    chmod 660 /etc/elasticsearch/elasticsearch.keystore
-    md5sum /etc/elasticsearch/elasticsearch.keystore > /etc/elasticsearch/.elasticsearch.keystore.initial_md5sum
+    chown root:elasticsearch "${ES_PATH_CONF}"/elasticsearch.keystore
+    chmod 660 "${ES_PATH_CONF}"/elasticsearch.keystore
+    md5sum "${ES_PATH_CONF}"/elasticsearch.keystore > "${ES_PATH_CONF}"/.elasticsearch.keystore.initial_md5sum
 else
     /usr/share/elasticsearch/bin/elasticsearch-keystore upgrade
 fi

distribution/packages/src/common/scripts/preinst

@@ -15,6 +15,13 @@ err_exit() {
     exit 1
 }
 
+# source the default env file
+if [ -f "${path.env}" ]; then
+    . "${path.env}"
+else
+  ES_PATH_CONF="${path.conf}"
+fi
+
 case "$1" in
 
     # Debian ####################################################