fix(workflow_engine): Finish dataSource => dataSources

[saponifi3d]

Description

This PR finishes the dataSource to dataSources transition on the API validator, removing data_source from validators and updating tests.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #102184      +/-   ##
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- Coverage   80.96%    80.90%   -0.06%     
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  Files        8747      8749       +2     
  Lines      389157    390152     +995     
  Branches    24729     24729              
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+ Hits       315082    315671     +589     
- Misses      73721     74127     +406     
  Partials      354       354              

[sentry]

Bug: Accessing [0] on an empty data_sources list, allowed by ListField without min_length, causes an IndexError.
_{Severity: CRITICAL | Confidence: 0.95}

🔍 Detailed Analysis

The data_sources field, defined as a serializers.ListField without a min_length constraint, allows an empty list [] to pass validation. When a client submits an empty list for data_sources, the code attempts to access validated_data.pop("data_sources")[0]. This operation on an empty list results in an IndexError: list index out of range, causing an unhandled exception. This occurs in the update() methods of UptimeDomainCheckFailureValidator, MetricIssueDetectorValidator, and MonitorIncidentDetectorValidator, as well as the create() method of MetricIssueDetectorValidator.

💡 Suggested Fix

Add min_length=1 to the data_sources ListField definitions in UptimeDomainCheckFailureValidator, MetricIssueDetectorValidator, and MonitorIncidentDetectorValidator. Alternatively, add a check for a non-empty list before accessing [0].

🤖 Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: src/sentry/uptime/endpoints/validators.py#L469-L472

Potential issue: The `data_sources` field, defined as a `serializers.ListField` without
a `min_length` constraint, allows an empty list `[]` to pass validation. When a client
submits an empty list for `data_sources`, the code attempts to access
`validated_data.pop("data_sources")[0]`. This operation on an empty list results in an
`IndexError: list index out of range`, causing an unhandled exception. This occurs in
the `update()` methods of `UptimeDomainCheckFailureValidator`,
`MetricIssueDetectorValidator`, and `MonitorIncidentDetectorValidator`, as well as the
`create()` method of `MetricIssueDetectorValidator`.

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[sentry]

Issues attributed to commits in this pull request

This pull request was merged and Sentry observed the following issues:

• ‼️ ThreadLeakAssertionError: <Thread(Thread-3 (run),... in local