[Form Recognizer] test failing in nightly runs

[v-yilinhu]

Form Recognizer nightly test runs are failing with:

Error Message
Azure.RequestFailedException : Failed to download the image from the submitted URL. The URL may either be invalid or the server hosting the image is experiencing some technical difficulties.
Status: 400 (Bad Request)
ErrorCode: 2001

Content:
{"error":{"code":"2001","message":"Failed to download the image from the submitted URL. The URL may either be invalid or the server hosting the image is experiencing some technical difficulties."}}

Headers:
ms-azure-ai-errorcode: REDACTED
x-envoy-upstream-service-time: 2191
apim-request-id: b8356e9d-dc59-4f5c-ae83-aff3cd9499b4
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
X-Content-Type-Options: nosniff
Date: Fri, 18 Jun 2021 04:47:08 GMT
Content-Length: 197
Content-Type: application/json; charset=utf-8

Stack Trace
at Azure.AI.FormRecognizer.FormRecognizerRestClient.AnalyzeWithCustomModelAsync(Guid modelId, Nullable1 includeTextDetails, IEnumerable1 pages, SourcePath fileStream, CancellationToken cancellationToken) in //sdk/formrecognizer/Azure.AI.FormRecognizer/src/Generated/FormRecognizerRestClient.cs:line 348
at Azure.AI.FormRecognizer.FormRecognizerClient.StartRecognizeCustomFormsFromUriAsync(String modelId, Uri formUri, RecognizeCustomFormsOptions recognizeCustomFormsOptions, CancellationToken cancellationToken) in //sdk/formrecognizer/Azure.AI.FormRecognizer/src/FormRecognizerClient.cs:line 1123
at Azure.Core.TestFramework.DiagnosticScopeValidatingInterceptor.<>c__DisplayClass4_01.<<WrapAsyncResultCore>g__Await|0>d.MoveNext() in /mnt/vss/_work/1/s/sdk/core/Azure.Core.TestFramework/src/Instrumentation/DiagnosticScopeValidatingInterceptor.cs:line 91 --- End of stack trace from previous location where exception was thrown --- at System.Threading.Tasks.ValueTask1.get_Result()
at Azure.Core.TestFramework.InstrumentResultInterceptor.InstrumentOperationInterceptor[T](IInvocation invocation, Func1 innerTask) in /mnt/vss/_work/1/s/sdk/core/Azure.Core.TestFramework/src/Instrumentation/InstrumentResultInterceptor.cs:line 60 at Azure.Core.TestFramework.DiagnosticScopeValidatingInterceptor.<>c__DisplayClass4_01.<g__Await|0>d.MoveNext() in /mnt/vss/_work/1/s/sdk/core/Azure.Core.TestFramework/src/Instrumentation/DiagnosticScopeValidatingInterceptor.cs:line 91
--- End of stack trace from previous location where exception was thrown ---
at System.Threading.Tasks.ValueTask1.get_Result() at Azure.Core.TestFramework.DiagnosticScopeValidatingInterceptor.<>c__DisplayClass5_01.<b__0>d.MoveNext() in /mnt/vss/_work/1/s/sdk/core/Azure.Core.TestFramework/src/Instrumentation/DiagnosticScopeValidatingInterceptor.cs:line 142
--- End of stack trace from previous location where exception was thrown ---
at System.Threading.Tasks.ValueTask1.get_Result() at Azure.Core.TestFramework.DiagnosticScopeValidatingInterceptor.ValidateDiagnosticScope[T](Func1 action, MethodInfo methodInfo, String source) in /mnt/vss/_work/1/s/sdk/core/Azure.Core.TestFramework/src/Instrumentation/DiagnosticScopeValidatingInterceptor.cs:line 165
at Azure.AI.FormRecognizer.Tests.RecognizeCustomFormsLiveTests.StartRecognizeCustomFormsFromUriThrowsForNonExistingContent(Boolean useTrainingLabels) in /mnt/vss/_work/1/s/sdk/formrecognizer/Azure.AI.FormRecognizer/tests/FormRecognizerClient/RecognizeCustomFormsLiveTests.cs:line 601
at Azure.AI.FormRecognizer.Tests.RecognizeCustomFormsLiveTests.StartRecognizeCustomFormsFromUriThrowsForNonExistingContent(Boolean useTrainingLabels) in /mnt/vss/_work/1/s/sdk/formrecognizer/Azure.AI.FormRecognizer/tests/FormRecognizerClient/RecognizeCustomFormsLiveTests.cs:line 607
at NUnit.Framework.Internal.TaskAwaitAdapter.GenericAdapter1.BlockUntilCompleted() at NUnit.Framework.Internal.MessagePumpStrategy.NoMessagePumpStrategy.WaitForCompletion(AwaitAdapter awaiter) at NUnit.Framework.Internal.AsyncToSyncAdapter.Await(Func1 invoke)
at NUnit.Framework.Internal.Commands.TestMethodCommand.RunTestMethod(TestExecutionContext context)
at NUnit.Framework.Internal.Commands.TestMethodCommand.Execute(TestExecutionContext context)
at NUnit.Framework.Internal.Commands.BeforeAndAfterTestCommand.<>c__DisplayClass1_0.b__0()
at NUnit.Framework.Internal.Commands.BeforeAndAfterTestCommand.RunTestMethodInThreadAbortSafeZone(TestExecutionContext context, Action action)

For more details check here:

• https://dev.azure.com/azure-sdk/internal/_build/results?buildId=953168&view=results