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

.drone.star

@@ -19,7 +19,6 @@ load(
 )
 load(
     "scripts/drone/pipelines/ci_images.star",
-    "publish_ci_build_container_image_pipeline",
     "publish_ci_windows_test_image_pipeline",
 )
 load(
@@ -51,7 +50,6 @@ def main(_ctx):
         }, "oss", "testing")] +
         integration_test_pipelines() +
         publish_ci_windows_test_image_pipeline() +
-        publish_ci_build_container_image_pipeline() +
         cronjobs() +
         secrets()
     )