CloudComposerExternalTaskSensor succeeds when all task instances are outside execution_range

`CloudComposerExternalTaskSensor` and `CloudComposerExternalTaskTrigger` appear to use the same window-checking pattern that previously caused `CloudComposerDAGRunSensor` to return success when all returned runs were outside the requested execution window.

Today the helper returns success as long as it does not find an in-window task instance in a disallowed state. If every returned task instance falls outside the requested `execution_range`, the helper still reports success instead of continuing to wait for a relevant in-window task instance.

This follow-up issue tracks:
- confirming the bug in both the sync sensor and deferrable trigger paths
- adding unit coverage for all-out-of-window, mixed-window, and boundary cases
- fixing both helpers so they only succeed when at least one task instance is inside the requested window and all in-window task instances satisfy the expected state set

This is intentionally tracked separately from the Dag-run sensor fix to keep that PR scoped to one behavior change.

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Drafted-by: Codex (GPT-5) (no human review before posting)