Don't announce "not checked"

The card view is checkable, and as a result, talkback announces "not
checked" when it gains a focus. To avoid that, make it non-checkable.

However, in the future, we may want to make it checkable again so that
it gets different background color when selected.

Bug: 376792411
Test: follow the instruction in the bug
Change-Id: I0d7fbb0e8a655697f5d52ba35629227537124bed
diff --git a/android/TerminalApp/res/layout/settings_list_item.xml b/android/TerminalApp/res/layout/settings_list_item.xml
index 645efbb..38c1d7b 100644
--- a/android/TerminalApp/res/layout/settings_list_item.xml
+++ b/android/TerminalApp/res/layout/settings_list_item.xml
@@ -22,7 +22,6 @@
     app:cardCornerRadius="28dp"
     app:checkedIcon="@null"
     android:focusable="true"
-    android:checkable="true"
     android:layout_height="wrap_content"
     android:layout_width="match_parent">
 
@@ -66,4 +65,4 @@
             app:layout_constraintStart_toEndOf="@id/settings_list_item_icon"
             app:layout_constraintEnd_toEndOf="parent" />
     </androidx.constraintlayout.widget.ConstraintLayout>
-</com.google.android.material.card.MaterialCardView>
\ No newline at end of file
+</com.google.android.material.card.MaterialCardView>