[Form Recognizer] [AAD] model management compose model failing in nightly runs

[v-jiaodi]

Form Recognizer nightly test runs are failing with:

Error message:
An unexpected error occurred.

Stack trace:
Error: An unexpected error occurred.
at toTrainingPollOperationState (/Users/runner/work/1/s/sdk/formrecognizer/ai-form-recognizer/dist-esm/src/lro/training.js:6:450)
at Object.poll (/Users/runner/work/1/s/sdk/formrecognizer/ai-form-recognizer/dist-esm/src/documentModelAdministrationClient.js:171:1068)
at processTicksAndRejections (internal/process/task_queues.js:95:5)
at Object.poll (/Users/runner/work/1/s/sdk/formrecognizer/ai-form-recognizer/src/lro/util/poller.ts:32:4)
at /Users/runner/work/1/s/sdk/formrecognizer/ai-form-recognizer/src/lro/util/poller.ts:37:79
at makeModel (/Users/runner/work/1/s/sdk/formrecognizer/ai-form-recognizer/test/public/training.spec.ts:227:23)
at async Promise.all (index 0)
at Context. (/Users/runner/work/1/s/sdk/formrecognizer/ai-form-recognizer/test/public/training.spec.ts:236:33)

For more details check here:

• https://dev.azure.com/azure-sdk/internal/_build/results?buildId=1153750&view=results

[witemple-msft]

I think this is related to the other ongoing FR issue: #18749

There is an ongoing service degradation with the preview API in canary. The service team are aware and investigating the cause.

[witemple-msft]

Closing in favor of #19604. Form Recognizer is currently a beta package targeting a preview REST API, so some amount of noise around service deployments and large changes is expected, but we'll continue to track issues with the Form API in the newest issue until they are resolved.

Thank you!