Fix new-AzureStorageContext in new PSH window failure

[blueww]

Fix the following issue:
After install the msi, and open a PowerShell window, create storage context will fail.

After debug, it seems caused by: In a new PSH window, get DefaultContext will get InvalidOperationException instead of return null.
• If import module, the SMProfile.DefaultContext will not be null, so get DefaultContext will success. So the issue not repro.
• If install msi and open window, SMProfile will be null so get DefaultContext will get exception. So the issue repro.

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[markcowl]

@blueww Not sure where this fix comes from, but it is too late for this release. Closing for now, can reopen after BUILD release.

[markcowl]

@blueww I have reproed the issue. I don't think this is the right fix for this issue. If it's important enough, we can discuss a hotfix for after the release goes out, but it is too late to make the release train at this point.

[blueww]

@markcowl
This bug is very severe， I believe many customer will meet it as there are many script has New-AzureStorageContext at the begin. (For dataplan blob/file manage)

We should fix it in May release. Please help on that.
Thanks!

[markcowl]

Closing in favor of #3938