feat: Create OrganizationContributors table in region dbs

[jasonyuezhang]

Updated version of https://github.com/getsentry/getsentry/pull/18880

1 pager with table info: https://www.notion.so/sentry/1-Pager-AI-Code-Review-Sub-Spec-2a98b10e4b5d80e29737f9c58f54efb9

Adds a new table that will hold all of the OrganizationContributors for a particular sentry org / integration_id combo.

If a user belongs and/or swaps to a separate Github org or sentry org, there will be a separate entry for that individual.

num_actions gets updated every time a successful seer request occurs, and num_actions gets cleared at the start of every billing period

Closes https://linear.app/getsentry/issue/ENG-5929/create-organizationcontributors-table

Legal Boilerplate

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.

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Copied from getsentry#103839
Original PR: getsentry#103839

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Introduce OrganizationContributors model and corresponding schema migration

This PR adds a new region-siloed Django model OrganizationContributors and a matching migration (1008_add_organization_contributors.py). The table captures per-organization, per-integration contributor metadata (external identifier, optional alias, action counter, timestamps) and enforces uniqueness on the (organization_id, integration_id, external_identifier) tuple. An index on date_updated is included to accelerate time-range queries. No application-level logic is added yet; future PRs will populate and mutate num_actions.

Key Changes

• Created src/sentry/models/organizationcontributors.py defining the OrganizationContributors model with region silo decorator and data fields
• Added migration src/sentry/migrations/1008_add_organization_contributors.py to create table sentry_organizationcontributors, unique constraint, and date_updated index
• Set __relocation_scope__ = RelocationScope.Excluded to keep rows from backup/restore flows

Affected Areas

• Database schema (new table)
• sentry models module

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This summary was automatically generated by @propel-code-bot

[propel-test-bot]

[PerformanceOptimization]

Missing index on num_actions field could cause performance issues when resetting action counts at billing period boundaries. Based on the PR description, num_actions gets cleared at the start of every billing period, which likely requires querying contributors by this field.

Consider adding an index if you'll be running queries like:

• Finding all contributors with actions to reset
• Filtering contributors by action count thresholds

If such queries are needed, add to the model's Meta:

indexes = [
    models.Index(fields=["date_updated"]),
    models.Index(fields=["num_actions"]),
]

Context for Agents

Missing index on `num_actions` field could cause performance issues when resetting action counts at billing period boundaries. Based on the PR description, `num_actions` gets cleared at the start of every billing period, which likely requires querying contributors by this field.

Consider adding an index if you'll be running queries like:
- Finding all contributors with actions to reset
- Filtering contributors by action count thresholds

If such queries are needed, add to the model's Meta:
```python
indexes = [
    models.Index(fields=["date_updated"]),
    models.Index(fields=["num_actions"]),
]
```

File: src/sentry/models/organizationcontributors.py
Line: 41

[propel-test-bot]

[BestPractice]

The migration defines external_identifier with db_index=True (line 41), but the model definition (line 25 in organizationcontributors.py) doesn't include this parameter. This inconsistency means the model and migration are out of sync.

The external_identifier field is part of a unique constraint, so it will be indexed as part of that constraint. However, if you need a separate index for queries that filter only by external_identifier, you should add db_index=True to the model:

external_identifier = models.CharField(max_length=255, db_index=True)

Or if the unique constraint index is sufficient, remove db_index=True from the migration.

Context for Agents

The migration defines `external_identifier` with `db_index=True` (line 41), but the model definition (line 25 in `organizationcontributors.py`) doesn't include this parameter. This inconsistency means the model and migration are out of sync.

The `external_identifier` field is part of a unique constraint, so it will be indexed as part of that constraint. However, if you need a separate index for queries that filter only by `external_identifier`, you should add `db_index=True` to the model:

```python
external_identifier = models.CharField(max_length=255, db_index=True)
```

Or if the unique constraint index is sufficient, remove `db_index=True` from the migration.

File: src/sentry/models/organizationcontributors.py
Line: 25