Move release-please config to .github/config/

Point the release-please workflow at the new config and manifest
paths and remove the old root-level files.
Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>

Author: zeitlinger

.github/workflows/release-please.yml

@@ -16,5 +16,8 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - uses: googleapis/release-please-action@16a9c90856f42705d54a6fda1823352bdc62cf38 # v4.4.0
+        id: release-please
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
+          config-file: .github/config/release-please-config.json
+          manifest-file: .github/config/.release-please-manifest.json