Chore: Upgrade Go to 1.21.5 (#79329)

* bumping grafanas go version to 1.21.5

* adding how to upgrade go doc

* removing the whole ci-build and corresponding pipelines

* clarifying that we have to run make drone

* fixing starlark linter and removing unused code

* Adding note about enterprise

* trying to change the underyling image to avoid musl issues

* only need to golang one

Dockerfile

@@ -3,7 +3,7 @@
 ARG BASE_IMAGE=alpine:3.18.3
 ARG JS_IMAGE=node:20-alpine3.18
 ARG JS_PLATFORM=linux/amd64
-ARG GO_IMAGE=golang:1.21.3-alpine3.18
+ARG GO_IMAGE=golang:1.21.5-alpine3.18
 
 ARG GO_SRC=go-builder
 ARG JS_SRC=js-builder