Tweak bluetooth text alignment

1. Remove the placeholder summary so it won't show blank summary
2. Update settings_entity_header to make text center_vertical,
so it could align with the icon.

Bug: 71742145
Test: Screenshot
Change-Id: I185114a4e0c8d996f218075a8633e802fabf3c66

res/layout-sw320dp/settings_entity_header.xml

@@ -45,6 +45,7 @@
         <LinearLayout
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
+            android:layout_gravity="center_vertical"
             android:paddingStart="16dp"
             android:paddingEnd="16dp"
             android:orientation="vertical">
@@ -57,8 +58,7 @@
                 android:singleLine="false"
                 android:ellipsize="marquee"
                 android:gravity="start"
-                android:textDirection="locale"
-                android:paddingTop="8dp" />
+                android:textDirection="locale" />
 
             <TextView
                 android:id="@+id/install_type"