Test using 0 as the override value of @subgroup_size

[Jiawei-Shao]

This patch adds a regression test that uses 0 as the override value of @subgroup_size for Dawn.

Issue: #4640

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Requirements for PR author:

• [*] All missing test coverage is tracked with "TODO" or .unimplemented().
• [*] New helpers are /** documented */ and new helper files are found in helper_index.txt.
• [*] Test behaves as expected in a WebGPU implementation. (If not passing, explain above.)
• [*] Test have be tested with compatibility mode validation enabled and behave as expected. (If not passing, explain above.)

Requirements for reviewer sign-off:

• Tests are properly located.
• Test descriptions are accurate and complete.
• Tests provide complete coverage (including validation control cases). Missing coverage MUST be covered by TODOs.
• Tests avoid over-parameterization (see case count report).

When landing this PR, be sure to make any necessary issue status updates.

[github-actions]

Results for build job (at bd2b1ce):

-webgpu:shader,validation,extension,subgroup_size_control:subgroup_size_override_must_be_power_of_2_at_pipeline_creation:* - 7 cases, 7 subcases (~1/case)
+webgpu:shader,validation,extension,subgroup_size_control:subgroup_size_override_must_be_power_of_2_at_pipeline_creation:* - 8 cases, 8 subcases (~1/case)
-TOTAL: 283186 cases, 2326094 subcases
+TOTAL: 283187 cases, 2326095 subcases