ci: PLT-478: Replace FM with actions-hub call

.github/workflows/follow-merge-sync-pr.yml

@@ -16,7 +16,6 @@ concurrency:
 
 env:
   DOWNSTREAM_REPOSITORY: "label-studio-enterprise"
-  DOWNSTREAM_EVENT_TYPE: "upstream_repo_update"
 
 jobs:
   sync:
@@ -60,53 +59,15 @@ jobs:
               ].join('\n')
             });
 
-      - name: Sync PR
-        uses: actions/github-script@v7
-        if: steps.check-membership.outputs.result == 'true'
-        id: sync-pr
-        env:
-          TITLE: ${{ github.event.pull_request.title }}
-          HEAD_REF: ${{ github.head_ref }}
-          BASE_REF: ${{ github.base_ref }}
-          PR_HEAD_REPOSITORY: ${{ github.event.pull_request.head.repo.full_name || github.repository }}
-          DOWNSTREAM_REPOSITORY: ${{ env.DOWNSTREAM_REPOSITORY }}
-          DOWNSTREAM_EVENT_TYPE: ${{ env.DOWNSTREAM_EVENT_TYPE }}
+      - name: Checkout Actions Hub
+        uses: actions/checkout@v4
         with:
-          github-token: ${{ secrets.GIT_PAT }}
-          script: |
-            const { repo, owner } = context.repo;
-            const pr_head_repository = process.env.PR_HEAD_REPOSITORY;
-            const downstream_repository = process.env.DOWNSTREAM_REPOSITORY;
-            const downstream_event_type = process.env.DOWNSTREAM_EVENT_TYPE;
-            const [pr_owner, pr_repo] = pr_head_repository.split('/');
-            const head_ref = process.env.HEAD_REF;
-            const base_ref = process.env.BASE_REF;
-            let event_action = '${{ github.event.action }}';
-            let commit_sha = '${{ github.event.pull_request.head.sha }}';
-            if (${{ github.event.pull_request.merged }}) {
-              event_action = 'merged';
-              commit_sha = '${{ github.sha }}';
-            }
-            const getCommitResponse = await github.rest.repos.getCommit({
-              owner: pr_owner,
-              repo: pr_repo,
-              ref: commit_sha
-            });
-            const result = await github.rest.repos.createDispatchEvent({
-              owner: owner,
-              repo: downstream_repository,
-              event_type: downstream_event_type,
-              client_payload: {
-                branch_name: head_ref,
-                base_branch_name: base_ref,
-                repo_name: '${{ github.repository }}',
-                commit_sha : commit_sha,
-                title: process.env.TITLE,
-                html_url: '${{ github.event.pull_request.html_url }}',
-                actor: '${{ github.actor }}',
-                author_username: getCommitResponse.data.commit.author.name,
-                author_email: getCommitResponse.data.commit.author.email,
-                event_action: event_action
-              }
-            });
-            return result
+          token: ${{ secrets.GIT_PAT }}
+          repository: HumanSignal/actions-hub
+          path: ./.github/actions-hub
+
+      - name: Dispatch Follow Merge Event
+        uses: ./.github/actions-hub/actions/follow-merge-dispatch
+        with:
+          github_token: ${{ secrets.GIT_PAT }}
+          downstream_repository: "${{ env.DOWNSTREAM_REPOSITORY }}"