Use pre-installed Az PowerShell module rather than downloading from PSGallery

[scbedd]

Last night we saw the following error.

Now, the pshell installer module already retries an download/install 3 times if it hits an exception. The issue here is that the repository threw a false-negative, which ended up crashing our pipeline.

Whether wrapping the entire script in a retry-loop is the solution, I'll leave up to the implementer.

[weshaggard]

This goes a little larger then smok-tests I've see it fail for normal live test runs as well. We need to come up with some way to reduce this error path when powershell gallery isn't responsive.

[weshaggard]

Looks like at least hosted image already includes these PS modules (https://github.com/actions/virtual-environments/blob/main/images/win/Windows2019-Readme.md#azure-powershell-modules) and we should try to use those instead of always doing a force install. From a quick look it seems windows and linux have 4.7 and mac has 4.6.1 and as long as those versions are enough we should just use those instead of install anything.

[weshaggard]

@heaths do you remember why we do a force install? (https://github.com/Azure/azure-sdk-tools/blob/master/eng/common/TestResources/setup-az-modules.yml#L24) as opposed to using the versions on the machine?

[heaths]

The force install has nothing to do with overriding what's installed. It's because you're prompted, by default, unless you pass -Force. If you want to use what's there, first do a get-module -list <whatever> to see if it's installed and, if not, you can install it. When I wrote these, I didn't realize the modules were on the image.

[mikeharder]

Fixed by #1137