Workaround for salt network interfaces bug

We need to save our manualy managed interfaces to different directory to
workaround salt bug that causes interface deconfiguration in
/etc/network/interfaces for interfaces manualy configured in
/etc/network/interfaces.d

Upstream-Bug: https://github.com/saltstack/salt/issues/40262

linux/network/interface.sls

 linux_interfaces_include_{{ interface_name }}:
   file.prepend:
   - name: /etc/network/interfaces
-  - text: 'source /etc/network/interfaces.d/*'
+  - text: |
+      source /etc/network/interfaces.d/*
+      # Workaround for Upstream-Bug: https://github.com/saltstack/salt/issues/40262
+      source /etc/network/interfaces.u/*
 
 ovs_port_{{ interface_name }}:
   file.managed:
-  - name: /etc/network/interfaces.d/ifcfg-{{ interface_name }}
+  - name: /etc/network/interfaces.u/ifcfg-{{ interface_name }}
+  - makedirs: True
   - source: salt://linux/files/ovs_port
   - defaults:
       port: {{ interface|yaml }}
 linux_interfaces_final_include:
   file.prepend:
   - name: /etc/network/interfaces
-  - text: 'source /etc/network/interfaces.d/*'
+  - text: |
+      source /etc/network/interfaces.d/*
+      # Workaround for Upstream-Bug: https://github.com/saltstack/salt/issues/40262
+      source /etc/network/interfaces.u/*
 
 {%- endif %}