fix(changeNoteType): hide headers and warning for cloze conversions

When converting to/from a cloze note type, the template tab incorrectly
showed "Current"/"New" column headers and a discarded-cards warning.
Now, when templates cannot be changed (any cloze conversion), the header
layout and removal warning are hidden alongside the spinners.

Also removes a duplicate visibility assignment line.

Fixes: #20873
Assisted-by: Claude Opus 4.7 - discussion & rubber duck
Signed-off-by: Hari Srinivasan <harisrini21@gmail.com>

Author: Haz3-jolt

AnkiDroid/src/main/java/com/ichi2/anki/dialogs/ChangeNoteTypeDialog.kt

@@ -488,13 +488,18 @@ class ChangeNoteTypeDialog : AnalyticsDialogFragment(R.layout.dialog_change_note
             lifecycleScope.launch {
                 viewModel.canChangeTemplatesFlow.collect { canChangeTemplates ->
                     binding.templatesContainer.isVisible = canChangeTemplates
-                    binding.templatesContainer.isVisible = canChangeTemplates
+                    binding.templatesHeaderLayout.isVisible = canChangeTemplates
+                    if (!canChangeTemplates) {
+                        binding.templateRemovalText.isVisible = false
+                    }
                 }
             }
 
             lifecycleScope.launch {
                 viewModel.discardedTemplatesFlow.collect { discarded ->
-                    showDiscardedTemplatesMessage(discarded)
+                    if (viewModel.canChangeTemplatesFlow.value) {
+                        showDiscardedTemplatesMessage(discarded)
+                    }
                 }
             }
         }