[ACR] Improve error message in running acr login in cloud shell

[djyou]

Fixes #5341

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[promptws]

View a preview at https://prompt.ws/r/Azure/azure-cli/5347
This is an experimental preview for @microsoft users.

[djyou]

@yugangw-msft I will rebase once your PR is merged.
/cc @sajayantony @SteveLasker @jluk @yolo3301
Any suggestions on the strings are appreciated.

[jluk]

Thanks for the quick PR @djyou - the error message looks sufficient to me.

Hopefully this mention of error enables users to realize they should use docker-machine or some other machine that can run docker sufficiently.