chore: Delete coverage-badge

At the moment, the code coverage action has just been failing. It's misleading when interpreting the status badge on the main branch. 

https://github.com/meta-llama/llama-stack/actions/workflows/coverage-badge.yml

.github/workflows/coverage-badge.yml

@@ -1,62 +0,0 @@
-name: Coverage Badge
-
-run-name: Creates PR for updating the code coverage badge
-
-on:
-  push:
-    branches: [ main ]
-    paths:
-      - 'llama_stack/**'
-      - 'tests/unit/**'
-      - 'uv.lock'
-      - 'pyproject.toml'
-      - 'requirements.txt'
-      - '.github/workflows/unit-tests.yml'
-      - '.github/workflows/coverage-badge.yml' # This workflow
-  workflow_dispatch:
-
-jobs:
-  unit-tests:
-    permissions:
-      contents: write  # for peter-evans/create-pull-request to create branch
-      pull-requests: write  # for peter-evans/create-pull-request to create a PR
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
-
-      - name: Install dependencies
-        uses: ./.github/actions/setup-runner
-
-      - name: Run unit tests
-        run: |
-          ./scripts/unit-tests.sh
-
-      - name: Coverage Badge
-        uses: tj-actions/coverage-badge-py@1788babcb24544eb5bbb6e0d374df5d1e54e670f # v2.0.4
-
-      - name: Verify Changed files
-        uses: tj-actions/verify-changed-files@a1c6acee9df209257a246f2cc6ae8cb6581c1edf # v20.0.4
-        id: verify-changed-files
-        with:
-          files: coverage.svg
-
-      - name: Commit files
-        if: steps.verify-changed-files.outputs.files_changed == 'true'
-        run: |
-          git config --local user.email "github-actions[bot]@users.noreply.github.com"
-          git config --local user.name "github-actions[bot]"
-          git add coverage.svg
-          git commit -m "Updated coverage.svg"
-
-      - name: Create Pull Request
-        if: steps.verify-changed-files.outputs.files_changed == 'true'
-        uses: peter-evans/create-pull-request@271a8d0340265f705b14b6d32b9829c1cb33d45e # v7.0.8
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
-          title: "ci: [Automatic] Coverage Badge Update"
-          body: |
-            This PR updates the coverage badge based on the latest coverage report.
-
-            Automatically generated by the [workflow coverage-badge.yaml](.github/workflows/coverage-badge.yaml)
-          delete-branch: true