🐛 Make floatingIPNetwork a pointer and if there's only one external network use it as default

[bilbobrovall]

What this PR does / why we need it: Makes floatingIPNetwork optional and automatically uses external network if there's only one

Which issue(s) this PR fixes:
Fixes #1997

Special notes for your reviewer:

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• if necessary:
  • includes documentation
  • adds unit tests

/hold

[k8s-ci-robot]

Hi @bilbobrovall. Thanks for your PR.

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[huxcrux]

/ok-to-test

[mdbooth]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bilbobrovall, mdbooth

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• OWNERS [mdbooth]

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[mdbooth]

/hold cancel