Remove support for non-Oracle Linux 9 operating systems

Security Onion now exclusively supports Oracle Linux 9. This removes
detection, setup, and update logic for Ubuntu, Debian, CentOS, Rocky,
AlmaLinux, and RHEL.

setup/so-setup

@@ -66,36 +66,6 @@ set_timezone
 # Let's see what OS we are dealing with here
 detect_os
 
-# Ubuntu/Debian whiptail pallete to make it look the same as CentOS and Rocky.
-set_palette >> $setup_log 2>&1
-
-if [[ $not_supported ]] && [ -z "$test_profile" ]; then
-	if [[ "$OSVER" == "focal" ]]; then
-		if (whiptail_focal_warning); then
-			true
-		else
-			info "User cancelled setup."
-			whiptail_cancel
-		fi
-	else
-		if (whiptail_unsupported_os_warning); then
-			true
-		else
-			info "User cancelled setup."
-			whiptail_cancel
-		fi
-	fi
-fi
-
-# we need to upgrade packages on debian prior to install and reboot if there are due to iptables-restore not running properly
-# if packages are updated and the box isn't rebooted
-if [[ $is_debian ]]; then
-	update_packages
-	if [[ -f "/var/run/reboot-required" ]] && [ -z "$test_profile" ]; then
-		whiptail_debian_reboot_required
-		reboot
-	fi
-fi
 
 # Check to see if this is the setup type of "desktop".
 is_desktop=
@@ -108,7 +78,7 @@ if [ "$setup_type" = 'desktop' ]; then
 	fi
 fi
 
-# Make sure if ISO is specified that we are dealing with CentOS or Rocky
+# Make sure if ISO is specified that we are dealing with an RPM-based install
 title "Detecting if this is an ISO install"
 if [[ "$setup_type" == 'iso' ]]; then
 	if [[ $is_rpm ]]; then