Fix SUSE guest networking

[ryan-ronnander]

Recent SUSE guests use NetworkManager and no longer include wicked or its ifcfg configuration files. openSUSE MicroOS has been affected since 2022 (#12777, static IPs silently fall back to DHCP). SLE and openSUSE Leap 16 removed wicked entirely, so every Leap 16 guest also fails after vagrant up:

/sbin/ifdown 'eth1' || true
mv '/tmp/vagrant-network-eth1-...' '/etc/sysconfig/network/ifcfg-eth1'
/sbin/ifup 'eth1'

bash: line 4: /sbin/ifdown: No such file or directory
mv: cannot move '/tmp/vagrant-network-eth1-...' to '/etc/sysconfig/network/ifcfg-eth1': No such file or directory

This fix follows the approach used for RHEL 10 guests in #13625: the network_scripts_dir capability detects the network configuration location, and configure_networks dispatches to the shared Vagrant::Util::GuestNetworks::Linux NetworkManager implementation when the wicked configuration directory is absent. The wicked path is unchanged for guests and older boxes that still use it (SLE/Leap 15.x).

Verified with vagrant-libvirt, using a private_network with a static IP:

• cloud-image/opensuse-leap-16.0: With this change vagrant up completes, static and DHCP-typed networks come up as NetworkManager profiles, and addresses persist across reloads.
• opensuse/MicroOS.x86_64 (the box from Setting a static IP on opensuse/MicroOS fails, uses DHCP instead #12777): the static address is applied (ipv4.method: manual) instead of silently staying on DHCP.
• cloud-image/opensuse-leap-15.6 (wicked): behavior unchanged, ifcfg path still used.

Fixes #12777

Note: current opensuse/MicroOS.x86_64 boxes ship with the interactive JeOS firstboot wizard enabled, which blocks first boot until it is answered on the VM console. That is a box packaging issue, outside the scope of this PR.

[hashicorp-cla-app]

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