[release-4.17] SDN-4919,SDN-5135: Graduate `UserDefinedNetworks` to GA

[openshift-cherrypick-robot]

This is an automated cherry-pick of #1988

/assign tssurya

[openshift-ci-robot]

@openshift-cherrypick-robot: Ignoring requests to cherry-pick non-bug issues: SDN-4919, SDN-5135

In response to [this](https://github.com/openshift/api/pull/1995): >This is an automated cherry-pick of #1988 > >/assign tssurya Instructions for interacting with me using PR comments are available [here](https://prow.ci.openshift.org/command-help?repo=openshift%2Fapi). If you have questions or suggestions related to my behavior, please file an issue against the [openshift-eng/jira-lifecycle-plugin](https://github.com/openshift-eng/jira-lifecycle-plugin/issues/new) repository.

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[trozet]

/lgtm

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[trozet]

/hold

after discussing with @JoelSpeed I think we should wait on lifting the feature gate for UDN in 4.17 until we have fully implemented it and have it tested in 4.17. It is now enabled in 4.18, and we will get sufficient CI coverage there across all jobs. Since 4.17 will be synced to 4.18, we can limit our risk of breaking 4.17 and still get the testing coverage we need in 4.18.

[openshift-ci[bot]]

@openshift-cherrypick-robot: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/e2e-azure	ed4fbd5e311d0eafbb87efceaa27d701e8c13c30	link	false	/test e2e-azure
ci/prow/e2e-aws-ovn-hypershift	ed4fbd5e311d0eafbb87efceaa27d701e8c13c30	link	true	/test e2e-aws-ovn-hypershift
ci/prow/verify	ed4fbd5e311d0eafbb87efceaa27d701e8c13c30	link	true	/test verify
ci/prow/images	ed4fbd5e311d0eafbb87efceaa27d701e8c13c30	link	true	/test images

Full PR test history. Your PR dashboard.

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