upload/koji: don't pass task_id to cg_init_build

Contrary to our assumption, we cannot initialize the build with the
link to the task. We can only update the link once the build has
completed.

This seems like a bug in koji, but we keep it like this for now.

.github/workflows/tests.yml

@@ -85,6 +85,7 @@ jobs:
       - name: Run unit tests
         run: |
           sudo internal/upload/koji/run-koji-container.sh start
+          koji --server=http://localhost/kojihub --user kojiadmin --password kojipass --authtype=password make-task image
           env KRB5_CONFIG=../../../.github/krb5.conf go test -v -race -covermode atomic -coverprofile=coverage.txt -tags koji_test ./internal/upload/koji
           sudo internal/upload/koji/run-koji-container.sh stop