refactor(contrib): remove and re-locate contrib folder content (#9316)

This PR refactors the contrib folder by deleting unnecessary files and
relocating others to a new repository.

Deleted the following files and folders:
- contrib/integration
- contrib/scripts
- contrib/tlstest
- contrib/local-test
- contrib/manual_test
- wait-for-it.sh

Relocated the following files and folders to
[github.com/hypermodeinc/dgraph-experimental](https://github.com/hypermodeinc/dgraph-experimental):
- contrib/config
- contrib/docker-build
- contrib/systemd

.github/workflows/ci-dgraph-system-upgrade-tests.yml

@@ -24,7 +24,7 @@ jobs:
   dgraph-upgrade-tests:
     if: github.event.pull_request.draft == false
     runs-on: warp-ubuntu-latest-x64-4x
-    timeout-minutes: 60
+    timeout-minutes: 90
     steps:
       - uses: actions/checkout@v4
         with: