Hide WebRAG button on Duck.ai Input Mode (#6419)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/488551667048375/task/1210830942545664?focus=true

### Description

- Hides the unimplemented WebRAG button.

### Steps to test this PR

- [ ] Open the Duck.ai Input Mode
- [ ] Verify that the WebRAG button is hidden

Author: joshliebe

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/inputscreen/ui/InputScreenFragment.kt

@@ -235,7 +235,8 @@ class InputScreenFragment : DuckDuckGoFragment(R.layout.fragment_input_screen) {
         }
         viewModel.visibilityState.onEach {
             binding.actionVoice.isInvisible = !it.voiceInputButtonVisible
-            binding.actionForceWebSearch.isVisible = it.forceWebSearchButtonVisible
+            // TODO: Uncomment when button is implemented
+            // binding.actionForceWebSearch.isVisible = it.forceWebSearchButtonVisible
         }.launchIn(lifecycleScope)
     }