Revert "Migrate to avb_add_hash_footer"

This reverts commit 26eca1fd2f8d13cd44fbff2ff031eaa4352fd534.

Reason for revert: Broke x86 build

Change-Id: Ia73721f073268aa059f577ab83afd3034c8c3ee5
diff --git a/virtualizationservice/src/payload.rs b/virtualizationservice/src/payload.rs
index 8378df3..7b8cb7f 100644
--- a/virtualizationservice/src/payload.rs
+++ b/virtualizationservice/src/payload.rs
@@ -365,7 +365,7 @@
         )?),
         writable: false,
     });
-    let bootconfig_image = "/apex/com.android.virt/etc/fs/microdroid_bootconfig.".to_owned()
+    let bootconfig_image = "/apex/com.android.virt/etc/microdroid_bootconfig.".to_owned()
         + match config.debugLevel {
             DebugLevel::NONE => "normal",
             DebugLevel::APP_ONLY => "app_debuggable",