Test flake: firewall rule form targets table

[david-crespo]

Never seen this before. It seems like the enter key press in the combobox passed through to submit the form as a whole, which threw everything off.

db94dea

https://github.com/oxidecomputer/console/actions/runs/13424227374/job/37503809801

I get failures about 1 or 2 out of 10 runs with:

npx playwright test --project=firefox -g 'form targets table' --repeat-each 10

[david-crespo]

#2705 seems to have improved it but not fixed it.

https://github.com/oxidecomputer/console/actions/runs/13443453825/job/37563220513