Remove deployment preview

Author: Ajay-singh1

netlify.toml

@@ -5,9 +5,6 @@
     BASEURL = "https://istio.io/"
 [context.branch-deploy.environment]
     BASEURL = "https://preliminary.istio.io/"
-
-[context.deploy-preview.environment]
-    BASEURL = "$DEPLOY_PRIME_URL/"
 [build.environment]
     # Consult the Docs WG before bumping Hugo.
     # Specifically, the version here should match docker/build-tools/Dockerfile in istio/tools,