Add the end-to-end test of the new loop's slice (M2.1, PR D part 2)

From an issue the scripted operator files and assigns in Gitea, through
the restatement, go-ahead, milestone and PR, a review comment answered
with a pushed fix, to an approved and merged PR and a closed item and
issue. The operator acts in Gitea through its own test account
(NISSE_OPERATOR_TOKEN) and in the item's thread through the in-memory
transport. Runs from scripts/e2e.sh.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

scripts/e2e.sh

@@ -17,4 +17,4 @@ else
     export NISSE_E2E_BUILD_HOST=${NISSE_E2E_BUILD_HOST:-nisse-dev.garrett-hall.com}
     export NISSE_E2E_BUILD_KEY=${NISSE_E2E_BUILD_KEY:-/root/nisse-e2e/ssh/id_ed25519}
 fi
-exec uv run pytest -m e2e -rs tests/integration/test_end_to_end.py "$@"
+exec uv run pytest -m e2e -rs tests/integration/test_end_to_end.py tests/integration/test_end_to_end_loop.py "$@"