fix: update file paths in entrypoint scripts

The commit updates the file paths in the entrypoint scripts to use the correct variables and directories. This ensures that the scripts work as intended and avoid any potential errors or issues.

entrypoint-healthcheck.sh

@@ -1,2 +1,2 @@
 #!/bin/bash
-exec gosu ${USERNAME} /app/*server monitor || exit 1
+exec gosu "${USERNAME}" /app/*server monitor || exit 1

entrypoint-user.sh

@@ -17,7 +17,7 @@ elif [ -d "/app/lgsm/modules" ]; then
 fi
 
 # Install game server
-if [ -z "$(ls -A -- "serverfiles" 2> /dev/null)" ]; then
+if [ -z "$(ls -A -- "/data/serverfiles" 2> /dev/null)" ]; then
   echo -e ""
   echo -e "Installing ${GAMESERVER}"
   echo -e "================================="