Fix flaky E2E tests

[AnatoliB]

This test always failed when running Start-E2ETest.ps1 without setting AzureWebJobsStorage environment variable:

AzureFunctions.PowerShell.Durable.SDK.E2E.ActivityTests.ActivityCanHaveQueueBinding (3ms): Error Message: System.TypeInitializationException : The type initializer for 'AzureFunctions.PowerShell.Durable.SDK.Tests.E2E.StorageHelpers' threw an exception.
---- System.ArgumentNullException : Value cannot be null. (Parameter 'connectionString')

The following test failed intermittently. I believe it was checking for a wrong condition in validateIntermediateResponse, and it passed only when this condition was not even evaluated (which depends on timing):

AzureFunctions.PowerShell.Durable.SDK.E2E\DurableClientTests.cs(243): error TESTERROR:
AzureFunctions.PowerShell.Durable.SDK.E2E.DurableClientTests.DurableClientSuspendOrchestration (15s 99ms): Error M essage: Assert.Equal() Failure
↓ (pos 0)
Expected: Suspended
Actual: Running
↑ (pos 0)
Stack Trace:
at AzureFunctions.PowerShell.Durable.SDK.E2E.DurableClientTests.<>c.b__7_0(Object intermediateStatusResponseBody) in Q:\Projects\Durable\Versioning\powershell\azure-functions-durable-powershell\test\E2E\AzureFunctions.PowerShell.Durable.SDK.E2E\DurableClientTests.cs:line 243