[Compute] Normalize storage type case in target region validation

[Hashim Khan (Hashim1999164)]

Summary

az sig image-version create --target-regions validated storage account types case-insensitively for the two-part form (region=Standard_LRS) but case-sensitively for the three-part form (region=1=Standard_LRS).

This compares with .lower() in the three-part path, matching the two-part path, and applies the same fix to the four-part --target-edge-zones validator. A unit test covers mixed-case three-part and two-part values.

Fixes #33880

Test plan

1. python -m unittest azure.cli.command_modules.vm.tests.latest.test_vm_actions.TestVMImage.test_process_gallery_image_version_namespace (or the local test module equivalent)
2. Confirm southeastasia=1=Standard_LRS no longer fails local validation

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Thank you for your contribution Hashim Khan (@Hashim1999164)! We will review the pull request and get back to you soon.

[Copilot]

Pull request overview

This PR fixes inconsistent case handling for storage account type validation in az sig image-version create parsing logic, making mixed-case values behave consistently across supported --target-regions/--target-edge-zones syntaxes.

Changes:

• Make three-part --target-regions parsing validate storage account types case-insensitively (matching the existing two-part behavior).
• Apply the same case-insensitive validation to four-part --target-edge-zones parsing.
• Add a unit test covering mixed-case --target-regions values (two-part and three-part).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/azure-cli/azure/cli/command_modules/vm/tests/latest/test_vm_actions.py	Adds test coverage for mixed-case storage types in --target-regions parsing.
src/azure-cli/azure/cli/command_modules/vm/_validators.py	Updates validators to check storage_account_type.lower() for three-part target regions and four-part target edge zones.

Suppressed comments (1)

src/azure-cli/azure/cli/command_modules/vm/_validators.py:2506

• Typo in error message: "forth" should be "fourth".

                    if storage_account_type.lower() not in storage_account_types_list:
                        raise ArgumentUsageError(
                            "usage error: {} is an invalid target edge zone argument. "
                            "The forth part is not a valid storage account type. "
                            "Storage account types must be one of {}.".format(t, storage_account_types_str))

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[Yong Zhang (yonzhan)]

Compute

[Hashim Khan (Hashim1999164)]

Pushed a follow up for the review notes.

Added a unit test in test_vm_actions.py for mixed case storage types on the four part --target-edge-zones form (region=edgeZone=replica=storageType). Also corrected the validator error text from "forth" to "fourth".