Add more grid dbs to Launcher3 backupscheme

- To enable homescreen restore with Launcher3/SearchLauncher dogfood, see bug for details

Bug: 210984712
Test: none
Change-Id: I398551bc6fece17aba163a27ef29c748d58ab90e
diff --git a/res/xml/backupscheme.xml b/res/xml/backupscheme.xml
index 299e92e..0f0dde2 100644
--- a/res/xml/backupscheme.xml
+++ b/res/xml/backupscheme.xml
@@ -2,6 +2,11 @@
 <full-backup-content xmlns:android="http://schemas.android.com/apk/res/android">
 
     <include domain="database" path="launcher.db" />
+    <include domain="database" path="launcher_6_by_5.db" />
+    <include domain="database" path="launcher_4_by_5.db" />
+    <include domain="database" path="launcher_4_by_4.db" />
+    <include domain="database" path="launcher_3_by_3.db" />
+    <include domain="database" path="launcher_2_by_2.db" />
     <include domain="sharedpref" path="com.android.launcher3.prefs.xml" />
     <include domain="file" path="downgrade_schema.json" />