[Experimenter Legacy] Experiments and Rollouts are marked as completed before they are disabled from Normandy

[data-sync-user]

[Affected versions]:

• Firefox Nightly 126.0a1

[Affected Platforms]:

• Windows 10 x64, Windows 11 x64, macOS 13.6.2, Ubuntu 22.04 x64

[Prerequisites]:

• Have a Firefox Nightly 126.0a1 installed.

[Steps to reproduce]:

1. Open the browser and navigate to the Legacy Experimenter page.
2. Set up any delivery with valid data for each step.
3. Mark all the required flags and save.
4. Send the delivery to Normandy and complete the flow there. (see any of the “How to …“ documents from here)
5. Approve the recipe in NDT.
6. Wait for the Experimenter legacy page to update to the “Accepted by Normandy” state.
7. Enable (Publish) the recipe in NDT.
8. Wait for the Experimenter legacy page to update to the “LIVE” state.
9. Wait for 0.5 - 2h and refresh the page.

[Expected result]:

• The delivery is still marked as LIVE.

[Actual result]:

• The delivery was marked as completed by the unknown-user@normandy.mozilla.com account.

[Notes]:

• The recipes are still Enabled in NDT and clients can read from them without issue. The issue seems to be constrained to the Experimenter Legacy site.
• It’s unclear at this point if this issue will affect the Production environment. The most recent Experiment is still marked as LIVE.
• Here’s a list of all experiments that were marked as completed by an unknown @mozilla.com account.

┆Issue is synchronized with this Jira Bug