[v11.3.x] CI: Support more version formats in publishing (#94750)

CI: Support more version formats in publishing (#94575)

* cleanup dead code
* add tests and rewrite publish grafanacom steps to reuse
* add pkg/build tests; don't upload CDN assets on grafana releases

(cherry picked from commit 7a2edd35d5)

pkg/build/validation/validation.go

@@ -1,9 +1,5 @@
 package validation
 
-import (
-	"context"
-)
-
 type ArtifactType int
 
 const (
@@ -15,13 +11,3 @@ type Artifact struct {
 	Type ArtifactType
 	URL  string
 }
-
-// ReleaseArtifacts generates a list of release artifacts
-func ReleaseArtifacts(version string) ([]Artifact, error) {
-	return nil, nil
-}
-
-// VerifyRelease tests that a that, given the information, a release will completed wholly and successfully.
-func VerifyRelease(ctx context.Context, version string) (bool, error) {
-	return false, nil
-}