Tweak clear all button layout UI

Add vertical margins to clear all button and add horizontal padding.

Bug: 114136250
Test: Manual test on marlin_svelte and emulated tablet (1280 x 800)
Change-Id: Iae8d6609ca1031947e8e8d90f526d9cbda070ee5
diff --git a/go/quickstep/res/layout/clear_all_button.xml b/go/quickstep/res/layout/clear_all_button.xml
index 003ee86..be76d53 100644
--- a/go/quickstep/res/layout/clear_all_button.xml
+++ b/go/quickstep/res/layout/clear_all_button.xml
@@ -23,7 +23,9 @@
         android:id="@+id/clear_all_button"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
+        android:layout_marginVertical="16dp"
         android:layout_gravity="center_horizontal"
+        android:paddingHorizontal="32dp"
         android:background="@drawable/clear_all_button"
         android:gravity="center"
         android:text="@string/recents_clear_all"