fix(ui-alerts,console): remove Alert live-region role warning

[ToMESSKa]

…x console log messages

INSTUI-5131

ISSUE:

• Alert warns that your live region must have role="alert", but role="alert" means assertive per WAI-ARIA, so even when you'd set liveRegionPoliteness="polite" (non-assertive), you got a warning asking for role="alert". It was likely a leftover before the liveRegionPoliteness prop was added. GitHub issue: Alert wants role="alert" added to live region #2276

Setting role="alert" is equivalent to setting aria-live="assertive" and aria-atomic="true". [...] Dynamic changes that are less urgent should use a less aggressive method, such as including aria-live="polite" or using an other live region role like status.
https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Reference/Roles/alert_role

TEST PLAN:

• test this example, it should not emit a warning

[github-actions]

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[github-actions]

Visual regression report

⚠️ Changes detected.

Status	Count
Unchanged	0
Changed	1
New	96
Removed	32

📊 View full report

Diff images (33)

alert.png — baseline no longer produced

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diff-demo.png — 6324 pixels differ

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_{Baselines come from the visual-baselines branch. They refresh on every merge to master.}