Use MARIADB_USAGE for MariaDB memory budget

my-cnf-gen.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-MARIADB_MEMORY_PERCENT=25
+MARIADB_USAGE="${MARIADB_USAGE:-25}"
 MIN_BUFFER_POOL_MB=256
 MAX_CONNECTIONS_MIN=80
 MAX_CONNECTIONS_MAX=300
@@ -12,7 +12,7 @@ Usage:
   my-cnf-gen.sh [--output PATH]
 
 Generates a conservative MariaDB 10.6 my.cnf for DirectAdmin servers.
-The InnoDB buffer pool is sized to about 25% RAM so other DA services
+The InnoDB buffer pool is sized from MARIADB_USAGE percent of RAM so other DA services
 such as web, exim, dovecot, redis and spam filtering keep enough memory.
 EOF
 }
@@ -87,7 +87,7 @@ calc_buffer_pool_mb() {
     local mem_mb="$1"
     local pool_mb
 
-    pool_mb=$((mem_mb * MARIADB_MEMORY_PERCENT / 100))
+    pool_mb=$((mem_mb * MARIADB_USAGE / 100))
     if (( pool_mb < MIN_BUFFER_POOL_MB )); then
         pool_mb="$MIN_BUFFER_POOL_MB"
     fi
@@ -152,7 +152,7 @@ generate_config() {
 # Generated by my-cnf-gen.sh for MariaDB 10.6 and DirectAdmin stack hosts.
 # Detected RAM: ${mem_mb}M
 # Detected CPU cores: ${cores}
-# MariaDB memory budget: ${MARIADB_MEMORY_PERCENT}% RAM
+# MariaDB memory budget: ${MARIADB_USAGE}% RAM
 
 [client]
 port=3306