fix openvswitch port assignment

[steiler]

fix #1533

[steiler]

waiting for patrick to double check the build

[pdumais]

when creating a lab, the ovsp port is created and added in the selected ovs bridge. That's good

if creating a lab that references a bridge that has not manually been created with ovs-vsctl, clab throws an error. But this is not a change in behaviour. ok

when destroying a lab, ovsp ports get deleted but their interface is not removed from the ovs bridge. Not a change in behaviour but it would be nice to fix that some day.

it is impossible to set the bridge to protocols=OpenFlow13 before launching clab. We can set the protocol version after clab
is launched. But this complicates automation scripts. It would be nice to get that fixed. This is not a change in behaviour but it is a bug. Want me to raise a separate ticket for that?

setting a default drop flow and then adding flows to patch likns together works as expected

So other than a few changes I'd like fixed, I'd say that this PR fixes the initial bug that I raised and behaviour is back to normal.

[pdumais]

using client := ovs.New(goOvs.Sudo(), ovs.FlowFormat("OXM-OpenFlow14"), ovs.Protocols("OpenFlow14"))
instead of c := goOvs.New(goOvs.Sudo(),)
may help.

This can be tested by setting the bridge mode: ovs-vsctl set bridge ovsbr1 protocols=OpenFlow13 before creating the lab

[codecov]

Codecov Report

Merging #1534 (5fbdd62) into main (dd86c24) will decrease coverage by 0.18%.
Report is 2 commits behind head on main.
The diff coverage is 7.14%.

❗ Current head 5fbdd62 differs from pull request most recent head 394014e. Consider uploading reports for the commit 394014e to get more accurate results

@@            Coverage Diff             @@
##             main    #1534      +/-   ##
==========================================
- Coverage   47.93%   47.75%   -0.18%     
==========================================
  Files         131      131              
  Lines       12622    12620       -2     
==========================================
- Hits         6050     6027      -23     
- Misses       5837     5860      +23     
+ Partials      735      733       -2     

Files Changed	Coverage Δ
links/endpoint_bridge.go	41.93% <0.00%> (ø)
links/link.go	59.57% <ø> (+0.16%)	⬆️
nodes/ovs/ovs.go	1.51% <0.00%> (-0.82%)	⬇️
links/link_veth.go	78.84% <100.00%> (-1.69%)	⬇️
nodes/bridge/bridge.go	60.97% <100.00%> (-0.93%)	⬇️

... and 2 files with indirect coverage changes