Use CheckboxSetting in memory settings dialog.

[polina-c]

See TODO in the code https://github.com/flutter/devtools/blob/57d637c4d57e2e679309d07dcfe743b191e9ed2a/packages/devtools_app/lib/src/screens/memory/panes/control/settings_dialog.dart

[srawlins]

Closing as resolved: MemorySettingsDialog now uses CheckboxSetting for configuring the Android memory chart setting.

If there is more work to do here, please let us know by filing a new issue with up to date information. Thanks!