CI: Build pre-release artifacts in GhA on merge to release branches and main. (#106779)

* Add grafana-build action and workflow

* Fix the --verify flag stalling on tar.gz builds

* Add event sources for main / release branches

* Update CODEOWNERS

.github/actionlint.yaml

@@ -0,0 +1,8 @@
+# These are just aliases to github-hosted runners
+self-hosted-runner:
+  labels:
+    - github-hosted-ubuntu-arm64
+    - github-hosted-ubuntu-arm64-large
+    - github-hosted-ubuntu-x64-small
+    - github-hosted-ubuntu-x64-large
+    - github-hosted-windows-x64-large