Remove systemd Install alias (#1470)

Alias is a list of additional names. Adding it's cannonical name
cause systemctl enable telegraf to show a warning "Too many levels of
symbolic links"

scripts/post-install.sh

@@ -37,6 +37,10 @@ chmod 755 $LOG_DIR
 if [[ -L /etc/init.d/telegraf ]]; then
     rm -f /etc/init.d/telegraf
 fi
+# Remove legacy symlink, if it exists
+if [[ -L /etc/systemd/system/telegraf.service ]]; then
+    rm -f /etc/systemd/system/telegraf.service
+fi
 
 # Add defaults file, if it doesn't exist
 if [[ ! -f /etc/default/telegraf ]]; then

scripts/telegraf.service

@@ -15,4 +15,3 @@ KillMode=control-group
 
 [Install]
 WantedBy=multi-user.target
-Alias=telegraf.service