Remove or replace unnecessary BackHandler calls (#4148)

* Remove/replace `BackHandler` calls:

- For `UserProfileView`, remove the redundant `BackHandler` -> `navigateUp()` call.
- For `SetupBiometricView`, remove the `enabled = true` parameter, as this is the default value.

features/lockscreen/impl/src/main/kotlin/io/element/android/features/lockscreen/impl/setup/biometric/SetupBiometricView.kt

@@ -31,7 +31,7 @@ fun SetupBiometricView(
     state: SetupBiometricState,
     modifier: Modifier = Modifier,
 ) {
-    BackHandler(true) {
+    BackHandler {
         state.eventSink(SetupBiometricEvents.UsePin)
     }
     HeaderFooterPage(