sync_client_software: remove unresolvable _gateway NTP entry from chrony.conf

Anaconda adds 'server _gateway iburst' as a fallback NTP source when
no NTP servers are specified in the kickstart. chronyd cannot resolve
the special hostname '_gateway' at startup, logging an error each boot.
The sourcedir /run/chrony-dhcp directive already handles DHCP-provided
NTP servers, making the _gateway line redundant.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

system_setup/sync_client_software.sh

@@ -10,6 +10,16 @@ if [ "$EUID" -ne 0 ]; then
     echo "Press any key to continue" && read -n 1 -s -r && exit 1
 fi
 
+# Remove 'server _gateway iburst' from chrony.conf — Anaconda adds it as a fallback but
+# _gateway is not resolvable by chronyd at startup; DHCP-sourced servers via sourcedir
+# /run/chrony-dhcp already cover NTP discovery so this line is redundant and noisy.
+_CHRONY_CONF="/etc/chrony.conf"
+if [ -f "${_CHRONY_CONF}" ] && grep -q "^server _gateway" "${_CHRONY_CONF}"; then
+    echo "Patching chrony.conf: removing unresolvable 'server _gateway' entry"
+    sed -i "/^server _gateway/d" "${_CHRONY_CONF}"
+    systemctl restart chronyd
+fi
+
 # Ensure krb5_validate = False in sssd.conf to restore offline auth
 # (SSSD >= 2.10.1 skips the CAP_DAC_READ_SEARCH raise in offline mode, so validate_tgt
 #  fails with EACCES before the cached-credential fallback is reached)