net-naming-scheme: disable NAMING_FIRMWARE_NODE_SUN

It seems that virtio devices always have "0" in
the firmware_node/sun. And because of that, udev will
always name the device ens0, which leads to collisions.
So let's disable it for now.

rhel-only: policy
Resolves: RHEL-55728

man/systemd.net-naming-scheme.xml

@@ -528,7 +528,7 @@
         <varlistentry>
           <term><constant>rhel-10.0-beta</constant></term>
 
-          <listitem><para>PCI slot number is now read from <constant>firmware_node/sun</constant> sysfs file.</para>
+          <listitem><para>Same as naming scheme <constant>v255</constant>.</para>
 
           <xi:include href="version-info.xml" xpointer="rhel-10.0.beta"/>
           </listitem>

src/shared/netif-naming-scheme.h

@@ -83,7 +83,7 @@ typedef enum NamingSchemeFlags {
         NAMING_RHEL_9_4 = NAMING_RHEL_9_3,
         NAMING_RHEL_9_5 = (NAMING_RHEL_9_4 & ~NAMING_BRIDGE_MULTIFUNCTION_SLOT) | NAMING_FIRMWARE_NODE_SUN,
 
-        NAMING_RHEL_10_0_BETA = NAMING_V255 | NAMING_FIRMWARE_NODE_SUN,
+        NAMING_RHEL_10_0_BETA = NAMING_V255,
 
         EXTRA_NET_NAMING_SCHEMES