Clarify watcher deferrable failure messaging

[pankajkoti]

The PR makes the following changes:

• Enrich WatcherTrigger failure events with explicit reason codes (model_failed vs producer_failed) and log producer task crashes so deferrable sensors can react accurately.
• Update DbtConsumerWatcherSensor.execute_complete to raise targeted messages for model and producer failures and otherwise exit cleanly.
• Align the watcher operator/trigger tests with the new payload shape and add coverage for the reason-specific messaging paths.

closes: #2123

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.82%. Comparing base (fa645d8) to head (ed6ea98).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

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##             main    #2124   +/-   ##
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  Coverage   97.81%   97.82%           
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  Files          92       92           
  Lines        5961     5968    +7     
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+ Hits         5831     5838    +7     
  Misses        130      130           

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[Copilot]

Pull Request Overview

This PR enhances error handling in the dbt watcher system by introducing explicit failure reasons to distinguish between model failures and producer task crashes. The changes enable deferrable sensors to provide more accurate and actionable error messages to users.

Key Changes:

• Added reason field to WatcherTrigger failure events to differentiate between model_failed and producer_failed scenarios
• Updated DbtConsumerWatcherSensor.execute_complete to raise targeted exceptions based on failure reason
• Enhanced logging in the trigger when producer task failures occur

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
cosmos/_triggers/watcher.py	Added reason codes to failure events and logging for producer failures
cosmos/operators/watcher.py	Refactored execute_complete to handle different failure reasons with specific error messages
tests/_triggers/test_watcher.py	Updated test expectations to match new payload structure with reason field
tests/operators/test_watcher.py	Added comprehensive test coverage for execute_complete failure scenarios

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[tatiana]

This looks great, thanks a lot, @pankajkoti !
Moving forward (in a follow up PR), if the model failed, would there be a possibility to give more details on the failure?

[pankajkoti]

Moving forward (in a follow up PR), if the model failed, would there be a possibility to give more details on the failure?

Yes, I guess it should be done and could be tacked as part of ticket #2072. I also added a comment about the same in the ticket