CI: Remove unused release_publisher scripts (#101019)

* Remove the unused `release_publisher` script.
* Remove the "whats new check" in Drone.
* Automatically set the What's New URL in releases based on the tagged version.

package.json

@@ -67,7 +67,7 @@
     "generate-apis": "yarn process-specs && rtk-query-codegen-openapi ./scripts/generate-rtk-apis.ts"
   },
   "grafana": {
-    "whatsNewUrl": "https://grafana.com/docs/grafana/next/whatsnew/whats-new-in-v11-5/",
+    "whatsNewUrl": "https://grafana.com/docs/grafana/next/whatsnew/whats-new-in-v%[1]s-%[2]s/",
     "releaseNotesUrl": "https://grafana.com/docs/grafana/next/release-notes/"
   },
   "devDependencies": {