Remove setup-upstream-remote.sh

It shouldn't be needed anymore.

Author: Kobzol

.github/workflows/ci.yml

@@ -111,9 +111,6 @@ jobs:
           # which then uses log commands to actually set them.
           EXTRA_VARIABLES: ${{ toJson(matrix.env) }}
 
-      - name: setup upstream remote
-        run: src/ci/scripts/setup-upstream-remote.sh
-
       - name: ensure the channel matches the target branch
         run: src/ci/scripts/verify-channel.sh