feat: add is_deleted soft-delete to ClickHouse IDENTITIES table

[10done]

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Changes

Fixes #7593

• Added is_deleted Bool DEFAULT false column to the ClickHouse IDENTITIES table via a new migration
• Extended the mapper and INSERT column list to carry is_deleted on every backfill row (defaults to false)
• Added write_identity_deletion_tombstone_to_clickhouse async task, dispatched from EdgeIdentity.delete() to tombstone deleted identities in real time
• Added AND i.is_deleted = false to the segment membership count query so deleted identities never appear in counts

How did you test this code?

DESCRIBE TABLE IDENTITIES` confirms `is_deleted Bool DEFAULT false` column exists after migration Inserted a live row (`alice`) and a tombstone (`bob`); query with `WHERE is_deleted = false` returns only `alice` Python assertions confirm `services.py` has the `is_deleted = false` filter and `tasks.py` has the correct INSERT column list and SQL

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.39%. Comparing base (cbcac64) to head (32cb19c).
⚠️ Report is 20 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7710      +/-   ##
==========================================
- Coverage   98.52%   98.39%   -0.13%     
==========================================
  Files        1444     1453       +9     
  Lines       54971    55870     +899     
==========================================
+ Hits        54161    54976     +815     
- Misses        810      894      +84     

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[matthewelwell]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a mechanism to handle deleted identities in ClickHouse by writing a tombstone row (with is_deleted=True) upon identity deletion, ensuring they are excluded from segment membership counts. It includes a ClickHouse migration, updates to the mapping logic, a new Celery task, and corresponding unit tests. The review feedback highlights a potential issue with write amplification and table bloat in multi-tenant environments, suggesting that we should verify if segment membership is enabled for the organization before writing the tombstone row.

[gemini-code-assist]

In a multi-tenant environment, writing tombstone rows for every deleted identity across all organizations—even those that do not have segment_membership_inspection enabled—will lead to unnecessary ClickHouse write amplification and table bloat. We should check if the organization has segment membership enabled before writing the tombstone.

    if not settings.CLICKHOUSE_ENABLED:
        logger.info(
            "tombstone.skipped",
            reason="clickhouse_not_configured",
            env_key=env_key,
            identifier=identifier,
        )
        return

    from environments.models import Environment

    try:
        environment = Environment.objects.select_related(
            "project__organisation"
        ).get(api_key=env_key)
    except Environment.DoesNotExist:
        logger.info(
            "tombstone.skipped",
            reason="environment_not_found",
            env_key=env_key,
            identifier=identifier,
        )
        return

    if not is_membership_enabled(environment.project.organisation):
        logger.info(
            "tombstone.skipped",
            reason="segment_membership_disabled",
            env_key=env_key,
            identifier=identifier,
        )
        return

[10done]

I have addressed this raised concern.