fix string used for rebranded Duck.ai setting sub-title (#6553)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/488551667048375/task/1211006141204529?focus=true

### Description
Fixes the rebranded Duck.ai settings sub-title and fixes "Learn More"
link for both variants.

### Steps to test this PR

- [x] Ensure you have the "subscriptionAIFeaturesRebranding" feature
flag enabled.
- [x] Verify the sub-title text in "AI settings" matches the copy and
"Learn More" link is clickable.
- [x] Disable "subscriptionAIFeaturesRebranding" feature flag.
- [x] Verify the sub-title text in "Duck.ai settings" matches the copy
and "Learn More" link is clickable.

### UI changes
See Asana task.

Author: LukasPaczos

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

@@ -86,17 +86,6 @@ class DuckChatSettingsActivity : DuckDuckGoActivity() {
 
         setContentView(binding.root)
 
-        binding.duckChatSettingsText.addClickableSpan(
-            textSequence = getText(R.string.duck_chat_settings_activity_description),
-            spans = listOf(
-                "learn_more_link" to object : DuckDuckGoClickableSpan() {
-                    override fun onClick(widget: View) {
-                        viewModel.duckChatLearnMoreClicked()
-                    }
-                },
-            ),
-        )
-
         setupToolbar(binding.includeToolbar.toolbar)
 
         observeViewModel()
@@ -120,7 +109,6 @@ class DuckChatSettingsActivity : DuckDuckGoActivity() {
         if (viewState.isRebrandingAiFeaturesEnabled) {
             binding.userEnabledDuckChatToggleRebranding.quietlySetIsChecked(viewState.isDuckChatUserEnabled, userEnabledDuckChatToggleListener)
             binding.duckChatSettingsTitle.setText(R.string.duck_chat_title_rebranding)
-            binding.duckChatToggleSettingsTitle.setText(R.string.duck_chat_settings_activity_description_rebranding)
             binding.userEnabledDuckChatToggle.gone()
             binding.userEnabledDuckChatToggleRebranding.show()
             binding.duckChatToggleSettingsTitle.setText(R.string.duck_chat_show_in_heading_rebranding)
@@ -129,14 +117,28 @@ class DuckChatSettingsActivity : DuckDuckGoActivity() {
         } else {
             binding.userEnabledDuckChatToggle.quietlySetIsChecked(viewState.isDuckChatUserEnabled, userEnabledDuckChatToggleListener)
             binding.duckChatSettingsTitle.setText(R.string.duck_chat_title)
-            binding.duckChatSettingsText.setText(R.string.duck_chat_settings_activity_description)
             binding.userEnabledDuckChatToggle.show()
             binding.userEnabledDuckChatToggleRebranding.gone()
             binding.duckChatToggleSettingsTitle.setText(R.string.duck_chat_show_in_heading)
             binding.showDuckChatSearchSettingsLink.setPrimaryText(getString(R.string.duck_chat_assist_settings_title))
             binding.showDuckChatSearchSettingsLink.setSecondaryText(getString(R.string.duck_chat_assist_settings_description))
         }
 
+        binding.duckChatSettingsText.addClickableSpan(
+            textSequence = if (viewState.isRebrandingAiFeaturesEnabled) {
+                getText(R.string.duck_chat_settings_activity_description_rebranding)
+            } else {
+                getText(R.string.duck_chat_settings_activity_description)
+            },
+            spans = listOf(
+                "learn_more_link" to object : DuckDuckGoClickableSpan() {
+                    override fun onClick(widget: View) {
+                        viewModel.duckChatLearnMoreClicked()
+                    }
+                },
+            ),
+        )
+
         binding.duckAiInputScreenEnabledToggle.apply {
             isVisible = viewState.shouldShowInputScreenToggle
             quietlySetIsChecked(viewState.isInputScreenEnabled, inputScreenToggleListener)