[MOL-22883][SV] Remove aria-readonly from location field button

[vuongthanh148]

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing apis or functionality to change)
• Documentation (change to documentation, comments or API descriptions)
• Tests (improvements to unit tests or E2E tests)
• Other (technical improvements, refactoring, or changes that don't fall into the above categories)

Description of changes

• Link to ticket
• Description of changes

DummyLocationField renders a <button> with aria-haspopup="dialog" and aria-readonly={readOnly}. aria-readonly is not a supported attribute for the button role, so accessibility scans (axe aria-allowed-attr, WCAG 4.1.2) report "ARIA attribute is not allowed: aria-readonly". The attribute was left orphaned when role="combobox" was removed from this element.

This removes aria-readonly from the button. Read-only behaviour is unchanged: LocationField.handleFocus already returns early when readOnly || disabled, so the modal does not open. aria-disabled and aria-haspopup are kept.

The same change is already on main (v3) via the linaria migration; this backports it to the v2 line, where v2.2.9 to v2.2.11 still ship the attribute.

Checklist

• Changes follow the project guidelines in CONTRIBUTING.md
• Looks good on mobile and tablet
• Updated documentation
• Added/updated unit tests