Revert "fix: agent now searches both /etc/servermanager and ~/.config for config"

This reverts commit fe997750ff.

install/agent-install.sh

@@ -53,15 +53,10 @@ cat > "$AGENT_BIN" << 'AGENTSCRIPT'
 #!/bin/bash
 set -e
 
-CONFIG_FILE=""
-if [ -f "/etc/servermanager/agent.conf" ]; then
-    CONFIG_FILE="/etc/servermanager/agent.conf"
-elif [ -f "$HOME/.config/servermanager/agent.conf" ]; then
-    CONFIG_FILE="$HOME/.config/servermanager/agent.conf"
-fi
+CONFIG_FILE="${1:-$HOME/.config/servermanager/agent.conf}"
 
 load_config() {
-    if [ -n "$CONFIG_FILE" ] && [ -f "$CONFIG_FILE" ]; then
+    if [ -f "$CONFIG_FILE" ]; then
         source "$CONFIG_FILE"
     fi
     SERVER_URL="${SERVER_URL:-}"