GA release of the JWT realm (#95398)

This PR removes the beta label for JWT realm feature to make it GA.

docs/changelog/95398.yaml

@@ -0,0 +1,9 @@
+pr: 95398
+summary: GA release of the JWT realm
+area: Authentication
+type: feature
+issues: []
+highlight:
+  title: GA release of the JWT realm
+  body: This PR removes the beta label for JWT realm feature to make it GA.
+  notable: true

x-pack/docs/en/security/authentication/jwt-realm.asciidoc

@@ -2,8 +2,6 @@
 [[jwt-auth-realm]]
 === JWT authentication
 
-beta::[]
-
 {es} can be configured to trust JSON Web Tokens (JWTs) issued from an external service
 as bearer tokens for authentication.