Fuchsia device is ephemeral. (#53717)

packages/flutter_tools/lib/src/fuchsia/fuchsia_device.dart

@@ -190,7 +190,7 @@ class FuchsiaDevice extends Device {
       id,
       platformType: PlatformType.fuchsia,
       category: null,
-      ephemeral: false,
+      ephemeral: true,
   );
 
   @override

packages/flutter_tools/test/general.shard/fuchsia/fuchsia_device_test.dart

@@ -97,6 +97,11 @@ void main() {
       ProcessManager: () => FakeProcessManager.any(),
     });
 
+    test('is ephemeral', () {
+      final FuchsiaDevice device = FuchsiaDevice('123');
+      expect(device.ephemeral, true);
+    });
+
     testUsingContext('supported for project', () async {
       final FuchsiaDevice device = FuchsiaDevice('123');
       globals.fs.directory('fuchsia').createSync(recursive: true);