[ELB] ip_group attribute in data_source/opentelekomcloud_lb_listener_v3

[anton-sidelnikov]

Summary of the Pull Request

Fix error with Invalid address to set: []string{"ip_group"}

PR Checklist

• Refers to: [ELB] listener data source error #2125
• Tests added/passed.
• Documentation updated.
• Schema updated.
• Release notes added.

Acceptance Steps Performed

=== RUN   TestDataSourceListenerV3_basic
=== PAUSE TestDataSourceListenerV3_basic
=== CONT  TestDataSourceListenerV3_basic
--- PASS: TestDataSourceListenerV3_basic (44.31s)
=== RUN   TestDataSourceListenerV3_byID
=== PAUSE TestDataSourceListenerV3_byID
=== CONT  TestDataSourceListenerV3_byID
--- PASS: TestDataSourceListenerV3_byID (43.54s)
PASS


Process finished with the exit code 0

[otc-zuul]

Build succeeded.
https://zuul.otc-service.com/t/eco/buildset/479f5c7569eb437a997b0ade6eae0659

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✔️ golang-make-test SUCCESS in 3m 29s
✔️ golang-make-vet SUCCESS in 2m 49s
✔️ tflint SUCCESS in 1m 59s
✔️ goreleaser-build SUCCESS in 8m 55s