Merge pull request #54647 from colemickens/crd-validation-beta

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Validation for CRD custom resources: feature gate promotion alpha->beta

**What this PR does / why we need it**: This promotes CRD Validation from **alpha** to **beta**.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #53829

**Special notes for your reviewer**: Issue #53829 discusses potential blockers to promoting CRD Validation to beta. None of the potential blockers are actual blockers, as they can all be accomplished without backward incompatible changes.

**Release note**:

```release-note
Promote validation for custom resources defined through CRD to beta
```

cc: @sttts @nikhita @mbohlool

api/openapi-spec/swagger.json

@@ -81289,7 +81289,7 @@
       "type": "string"
      },
      "validation": {
-      "description": "Validation describes the validation methods for CustomResources This field is alpha-level and should only be sent to servers that enable the CustomResourceValidation feature.",
+      "description": "Validation describes the validation methods for CustomResources",
       "$ref": "#/definitions/io.k8s.apiextensions-apiserver.pkg.apis.apiextensions.v1beta1.CustomResourceValidation"
      },
      "version": {