[GSoC 2026] Active cleanup of orphaned subscriptions for the taxirides topic

[HansMarcus01]

Summary of Changes

This pull request switches the execution mode of the Pub/Sub subscription cleaner for NYC taxi rides from simulation to active deletion by changing dry_run=True to dry_run=False inside:
stale_cleaner.py ➔ clean_pubsub_subscriptions()

Why This Change is Safe (7-Day Empirical Validation)

Prior to enabling active deletion, we ran the subscription cleaner in dry_run=True (Simulation Mode) for 7 days (from August 4, 2026, to August 11, 2026).

We monitored the state of the tracked resources by periodically downloading and analyzing the JSON audit state stored in GCS:

gs://apache-beam-testing-pabloem/stale_cleaner/pubsub_subscription.json

Key Empirical Findings:

• 100% Resource Abandonment: Multiple subscriptions under the pattern taxirides-realtime_beam_-... created on August 4 remained active, completely unconsumed, and were continuously updated every single day until August 11 without being acknowledged.
• Daily Accumulation Pattern: Between 4 and 5 new orphaned subscriptions were added daily and remained in the backlog.

JSON State Evidence (August 11 Audit):

{
    "projects/apache-beam-testing/subscriptions/taxirides-realtime_beam_-6413074580631200911": {
        "resource_name": "projects/apache-beam-testing/subscriptions/taxirides-realtime_beam_-6413074580631200911",
        "creation_date": "2026-08-04T00:53:24.441535",
        "last_update_date": "2026-08-11T12:24:57.889076"
    },
    "projects/apache-beam-testing/subscriptions/taxirides-realtime_beam_3858484106805878348": {
        "resource_name": "projects/apache-beam-testing/subscriptions/taxirides-realtime_beam_3858484106805878348",
        "creation_date": "2026-08-04T00:53:24.441562",
        "last_update_date": "2026-08-11T12:24:57.889077"
    }
}

Verification & Testing

• Unit test have been run successfully
• No other prefixes are impacted; the active deletion only targets the explicit NYC taxi prefix taxirides-realtime_beam_.

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