fix(service): explicitly set user in systemd definition (#11066)

Previously, no User clause was present.  While this still made systemd
run kong under the 'root' user id, the HOME environment variable would
not be set in the Kong process.  This caused the datafile library to
fail with various error conditions.

CHANGELOG.md

@@ -66,6 +66,9 @@
   [#10896](https://github.com/Kong/kong/pull/10896)
 - Fix a bug when worker consuming dynamic log level setting event and using a wrong reference for notice logging
   [#10897](https://github.com/Kong/kong/pull/10897)
+- Added a `User=` specification to the systemd unit definition so that
+  Kong can be controlled by systemd again.
+  [#11066](https://github.com/Kong/kong/pull/11066)
 
 #### Admin API
 

build/package/kong.service

@@ -4,6 +4,7 @@ Documentation=https://docs.konghq.com/
 After=syslog.target network.target remote-fs.target nss-lookup.target
 
 [Service]
+User=root
 ExecStartPre=/usr/local/bin/kong prepare -p /usr/local/kong
 ExecStart=/usr/local/openresty/nginx/sbin/nginx -p /usr/local/kong -c nginx.conf
 ExecReload=/usr/local/bin/kong prepare -p /usr/local/kong