Description of problem:
Update portgroup of ovs interface, the port tag is cleared unexpectedly.

Version-Release number of selected component (if applicable):
libvirt-8.5.0-6.el9.x86_64
openvswitch2.15-2.15.0-70.el9fdp.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Create an openvswitch bridge

1. ovs-vsctl show
   ce606951-de6b-4515-9280-44b2a6766a57
   Bridge "ovsbr0"
   Port "ovsbr0"
   Interface "ovsbr0"
   type: internal
   Port "eno8303"
   Interface "eno8303"
   ovs_version: "2.15.6"

2. Create an openvswitch network:
<network>
<name>ovs-net</name>
<uuid>1546c287-e22f-41c5-8eef-12ccb8a54af6</uuid>
<forward mode='bridge'/>
<bridge name='ovsbr0'/>
<vlan trunk='yes'>
<tag id='42' nativeMode='untagged'/>
<tag id='47'/>
</vlan>
<virtualport type='openvswitch'>
<parameters interfaceid='09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f'/>
</virtualport>
<portgroup name='dontpanic'>
<vlan>
<tag id='42'/>
</vlan>
</portgroup>
</network>

3. Start a vm

4. Attach a openvswitch interface to vm:

1. virsh attach-interface vm111 --type network --source ovs-net --model virtio
   Interface attached successfully

1. virsh dumpxml vm111 --xpath //interface
   <interface type="bridge">
   <mac address="52:54:00:07:7e:14"/>
   <source network="ovs-net" portid="555b1703-8f01-4f74-b15d-674b0c5e695a" bridge="ovsbr0"/>
   <vlan trunk="yes">
   <tag id="42" nativeMode="untagged"/>
   <tag id="47"/>
   </vlan>
   <virtualport type="openvswitch">
   <parameters interfaceid="09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f"/>
   </virtualport>
   <target dev="vnet3"/>
   <model type="virtio"/>
   <alias name="net0"/>
   <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
   </interface>

1. ovs-vsctl show
   ce606951-de6b-4515-9280-44b2a6766a57
   Bridge ovsbr0
   Port ovsbr0
   Interface ovsbr0
   type: internal
   Port vnet3
   tag: 42
   trunks: [42, 47]
   Interface vnet3
   Port eno8303
   Interface eno8303
   ovs_version: "2.15.6"

5. Update interface portgroup:

1. cat ovs-inc.xml
   <interface type="network">
   <mac address="52:54:00:e9:a0:ba"/>
   <source network='ovs-net' portgroup='dontpanic'/>
   <model type="virtio"/>
   <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
   </interface>

1. virsh update-device vm111 ovs-inc.xml
   Device updated successfully

6. Check the updated interface:

1. virsh dumpxml vm111 --xpath //interface
   <interface type="bridge">
   <mac address="52:54:00:e9:a0:ba"/>
   <source network="ovs-net" portgroup="dontpanic" portid="a31b4f86-cfe7-4951-b23a-1f6465df7345" bridge="ovsbr0"/>
   <vlan>
   <tag id="42"/>
   </vlan>
   <virtualport type="openvswitch">
   <parameters interfaceid="09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f"/>
   </virtualport>
   <target dev="vnet4"/>
   <model type="virtio"/>
   <alias name="net0"/>
   <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
   </interface>

1. ovs-vsctl show
   ce606951-de6b-4515-9280-44b2a6766a57
   Bridge ovsbr0
   Port ovsbr0
   Interface ovsbr0
   type: internal
   Port eno8303
   Interface eno8303
   Port vnet4
   Interface vnet4
   ovs_version: "2.15.6"

Actual results:
When updating interface portgroup, ovs port tag is cleared.

Expected results:
Updating interface portgroup should fail like:

1. virsh update-device rhel interface.xml
   error: Failed to update device from interface.xml
   error: internal error: Unable to set vlan configuration on port vnet4

Additional info:
1. Check the syslog:
ovs-vsctl[286450]: ovs|00001|vsctl|INFO|Called as ovs-vsctl --timeout=5 – --if-exists clear Port vnet4 tag – --if-exists clear Port vnet4 trunk – --if-exists clear Port vnet4 vlan_mode