CI: Replace enterprise check (#62359)

* Add steps in the pipeline for cloning enterprise when running PR tests.
* Removed enterprise-check from the github action workflows, and removed it from the codeowners file.

.github/workflows/enterprise-pr-check.yml

@@ -1,26 +0,0 @@
-name: Enterprise PR check
-on:
-  pull_request:
-    branches:
-      - main
-      - 'v[0-9]+.[0-9]+.x'
-jobs:
-  dispatch:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout Actions
-        uses: actions/checkout@v2
-        with:
-          repository: "grafana/grafana-github-actions"
-          path: ./actions
-          ref: main
-      - name: Install Actions
-        run: npm install --production --prefix ./actions
-      - name: Repository Dispatch
-        uses: ./actions/repository-dispatch
-        with:
-          token: ${{ secrets.GH_BOT_ACCESS_TOKEN }}
-          repository: grafana/grafana-enterprise
-          event_type: oss-pull-request
-          client_payload:
-            '{"source_sha": "${{ github.event.pull_request.head.sha }}", "source_branch": "${{ github.head_ref }}", "target_branch": "${{ github.base_ref }}", "pr_number": "${{ github.event.number }}"}'