fix(priority-overflow): avoid teardown notifications

[bsunderhus]

Summary

• move the unmount fix into @fluentui/priority-overflow, where teardown notifications are dispatched
• reset the overflow snapshot during disconnect() without broadcasting a final subscriber update
• add manager regression coverage for disconnect-time subscriber notifications
• add the required beachball patch change file for @fluentui/priority-overflow

Testing

• yarn check:change
• yarn nx run priority-overflow:test --runTestsByPath src/overflowManager.test.ts

[github-actions]

📊 Bundle size report

Package & Exports	Baseline (minified/GZIP)	PR	Change
priority-overflow createOverflowManager	5.358 kB 2.168 kB	5.357 kB 2.168 kB	-1 B
react-charts AreaChart	404.33 kB 126.47 kB	404.329 kB 126.469 kB	-1 B -1 B
react-charts DeclarativeChart	754.979 kB 221.561 kB	754.978 kB 221.556 kB	-1 B -5 B
react-charts DonutChart	315.101 kB 97.163 kB	315.1 kB 97.161 kB	-1 B -2 B
react-charts FunnelChart	306.342 kB 93.907 kB	306.341 kB 93.907 kB	-1 B
react-charts GanttChart	387.387 kB 120.871 kB	387.386 kB 120.871 kB	-1 B
react-charts GaugeChart	314.434 kB 96.549 kB	314.433 kB 96.548 kB	-1 B -1 B
react-charts GroupedVerticalBarChart	395.541 kB 123.696 kB	395.54 kB 123.695 kB	-1 B -1 B
react-charts HeatMapChart	389.495 kB 121.928 kB	389.494 kB 121.928 kB	-1 B
react-charts HorizontalBarChart	294.867 kB 89.75 kB	294.866 kB 89.744 kB	-1 B -6 B
react-charts Legends	234.403 kB 70.457 kB	234.402 kB 70.454 kB	-1 B -3 B
react-charts LineChart	415.681 kB 129.6 kB	415.68 kB 129.602 kB	-1 B 2 B
react-charts PolarChart	343.354 kB 107.407 kB	343.353 kB 107.405 kB	-1 B -2 B
react-charts ScatterChart	395.007 kB 123.647 kB	395.006 kB 123.651 kB	-1 B 4 B
react-charts VerticalBarChart	431.939 kB 128.619 kB	431.938 kB 128.619 kB	-1 B
react-charts VerticalStackedBarChart	401.559 kB 125.101 kB	401.558 kB 125.102 kB	-1 B 1 B
react-components react-components: entire library	1.293 MB 325.78 kB	1.293 MB 325.786 kB	-1 B 6 B
react-headless-components-preview react-headless-components-preview: entire library	247.532 kB 71.414 kB	247.531 kB 71.417 kB	-1 B 3 B
react-overflow hooks only	9.053 kB 3.227 kB	9.052 kB 3.227 kB	-1 B

Unchanged fixtures

Package & Exports	Size (minified/GZIP)
react-breadcrumb @fluentui/react-breadcrumb - package	103.012 kB 28.827 kB
react-charts HorizontalBarChartWithAxis	63 B 83 B
react-charts SankeyChart	212.023 kB 68.066 kB
react-charts Sparkline	80.888 kB 26.864 kB
react-components react-components: Button, FluentProvider & webLightTheme	66.281 kB 19.002 kB
react-components react-components: Accordion, Button, FluentProvider, Image, Menu, Popover	225.836 kB 67.998 kB
react-components react-components: FluentProvider & webLightTheme	39.504 kB 13.112 kB
react-portal-compat PortalCompatProvider	5.341 kB 2.146 kB
react-timepicker-compat TimePicker	140.677 kB 45.99 kB

_{🤖 This report was generated against 9c8dada6dc1d4ade2f59049748d93a3ba5802427}

[github-actions]

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