Migrate to avb_add_hash_footer

Replace custom genrules with the new build rule for AVB signing images.

Test: build and microdroid tests
Bug: 234564414
Bug: 185115783
Change-Id: I7886ff2695c6892de4be60db47c652b100515787
diff --git a/microdroid/microdroid.json b/microdroid/microdroid.json
index aff0b7b..bf72c6e 100644
--- a/microdroid/microdroid.json
+++ b/microdroid/microdroid.json
@@ -1,5 +1,5 @@
 {
-  "bootloader": "/apex/com.android.virt/etc/microdroid_bootloader",
+  "bootloader": "/apex/com.android.virt/etc/fs/microdroid_bootloader",
   "disks": [
     {
       "partitions": [
@@ -30,7 +30,7 @@
       "partitions": [
         {
           "label": "uboot_env",
-          "path": "/apex/com.android.virt/etc/uboot_env.img",
+          "path": "/apex/com.android.virt/etc/fs/uboot_env.img",
           "writable": false
         }
       ],