Use backend-meta edition of issue triage workflow

Uses matrix-org/backend-meta#14.

.github/workflows/triage-incoming.yml

@@ -5,24 +5,11 @@ on:
     types: [ opened ]
 
 jobs:
-  add_new_issues:
-    name: Add new issues to the triage board
-    runs-on: ubuntu-latest
-    steps:
-      - uses: octokit/graphql-action@v2.x
-        id: add_to_project
-        with:
-          headers: '{"GraphQL-Features": "projects_next_graphql"}'
-          query: |
-              mutation add_to_project($projectid:ID!,$contentid:ID!) {
-                addProjectV2ItemById(input: {projectId: $projectid contentId: $contentid}) {
-                item {
-                  id
-                  }
-                }
-              }
-          projectid: ${{ env.PROJECT_ID }}
-          contentid: ${{ github.event.issue.node_id }}
-        env:
-          PROJECT_ID: "PVT_kwDOAIB0Bs4AFDdZ"
-          GITHUB_TOKEN: ${{ secrets.ELEMENT_BOT_TOKEN }}
+  triage:
+    uses: matrix-org/backend-meta/.github/workflows/triage-incoming.yml@v1
+    with: 
+      project_id: 'PVT_kwDOAIB0Bs4AFDdZ'
+      content_id: ${{ github.event.issue.node_id }}
+    secrets: 
+      github_access_token: ${{ secrets.ELEMENT_BOT_TOKEN }}
+