[release-11.5.5] CI: move workflows/actions to actions (#104749)

CI: move workflows/actions to actions (#104711)

* move workflows/actions to actions

* rerun actions

* fix setup-go v5

* unpinned unnecessary pins

* update CODEOWONERS

* update CODEOWONERS

* remove remove-milestone from codeowners

* remove bad key

(cherry picked from commit 2436b4e097)

.github/workflows/backend-code-checks.yml

@@ -1,5 +1,4 @@
 name: Backend Code Checks
-description: Validate go.mod and OpenAPI specifications
 
 on:
   pull_request:
@@ -24,11 +23,11 @@ jobs:
     name: Validate Backend Configs
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: actions/checkout@v4
         with:
           persist-credentials: false
       - name: Setup Go
-        uses: actions/setup-go@111f3307d8850f501ac008e886eec1fd1932a34
+        uses: actions/setup-go@v5
         with:
           # Explicitly set Go version to 1.24.1 to ensure consistent OpenAPI spec generation
           # The crypto/x509 package has additional fields in Go 1.24.1 that affect the generated specs