Compact classic Settings layout

[wiresock]

Summary

• remove the empty rows left by unavailable update and notification settings in classic/non-UWP builds
• derive the compaction offsets from the scaled controls so the layout remains consistent on Windows 7 and at non-default DPI
• preserve the existing UWP layout and add regression coverage for both variants

Verification

• Release x86 test suite: 218 passed, 0 failed, 1 skipped
• Release UWP x86 test suite: 218 passed, 0 failed, 1 skipped
• dotnet format whitespace verification
• independent code review: no actionable findings