[Fix] snapshot configuration update with kms key

[anton-sidelnikov]

Summary of the Pull Request

PR Checklist

• Refers to: CSS snapshot configuration - updating period in creation_policy results in an error (CSS.0001) #2769
• Tests added/passed.
• Documentation updated.
• Schema updated.
• Release notes added.

Acceptance Steps Performed

=== RUN   TestResourceCSSSnapshotConfigurationV1_basic
=== PAUSE TestResourceCSSSnapshotConfigurationV1_basic
=== CONT  TestResourceCSSSnapshotConfigurationV1_basic
--- PASS: TestResourceCSSSnapshotConfigurationV1_basic (832.78s)
=== RUN   TestAccCheckCSSV1Validation
--- PASS: TestAccCheckCSSV1Validation (3.89s)
PASS

Process finished with the exit code 0

[otc-zuul]

Build succeeded.
https://zuul.otc-service.com/t/eco/buildset/8987ec6b9aee4eedafdc3c8eed50eaae

✔️ build-otc-releasenotes SUCCESS in 4m 09s
✔️ noop SUCCESS in 0s
✔️ otc-golangci-lint SUCCESS in 3m 33s
✔️ golang-make-test SUCCESS in 3m 56s
✔️ golang-make-vet SUCCESS in 2m 41s
✔️ tflint SUCCESS in 1m 55s
✔️ goreleaser-build SUCCESS in 7m 25s