Remove neutron network attachment default

[karelyatin]

networkAttachment is unnecessary for the known deployment types, so remove it's usage.

Related-Issue: #OSPRH-38470

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[centosinfra-prod-github-app]

Build failed (check pipeline). Post recheck (without leading slash)
to rerun all jobs. Make sure the failure cause has been resolved before
you rerun jobs.

https://gateway-cloud-softwarefactory.apps.ocp.cloud.ci.centos.org/zuul/t/rdoproject.org/buildset/a8e8e2fa1b7a41b2af40e5871e076b73

✔️ noop SUCCESS in 0s
❌ adoption-standalone-to-crc-ceph FAILURE in 2h 00m 51s
❌ adoption-standalone-to-crc-no-ceph NODE_FAILURE Node(set) request 100-0000225119 failed in 0s

[karelyatin]

main is broken since S2i Switch, required patches should go to 18-stable unless and until plan later changes to fix and reopen it