fix(material/list): remove pointer cursor for disabled selection list radios

[EduardF1]

Fixes #31937.

Summary

• Ensures disabled single-selection list radios do not keep the MDC radio pointer cursor.
• Adds a regression spec for disabled single-selection lists.

Validation

• pnpm install --frozen-lockfile
• pnpm exec prettier --check src/material/list/list.scss src/material/list/selection-list.spec.ts
• pnpm exec stylelint src/material/list/list.scss
• git --no-pager diff --check

Note: pnpm -s bazelisk test //src/material/list:unit_tests --test_output=errors was attempted after bazel mod deps --lockfile_mode=update, but Bazel analysis failed locally on Windows because no @@rules_sass+//src/toolchain:toolchain_type toolchain matched.

[google-cla]

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[EduardF1]

@googlebot I signed it!

[EduardF1]

Hi — I've signed the CLA but the check still shows as failing. Could someone re-trigger the CLA verification? Thanks!

[EduardF1]

Hi! Could I request a review from @mmalerba and @wagnermaciel? You've both been very active reviewing Material list/selection-list changes. Thanks!

[EduardF1]

I have signed the Google CLA (email: fischerszavaeduard@gmail.com). Could a maintainer please re-run the CLA check? Thank you!