Use protobuf 2.x instead of 3.x

Bug: 270895633
Test: build
Change-Id: Id52bdc89ff223a4a0f538ca4fddae5359256a9f1
diff --git a/microdroid/payload/metadata/Android.bp b/microdroid/payload/metadata/Android.bp
index cd182fc..e3138e8 100644
--- a/microdroid/payload/metadata/Android.bp
+++ b/microdroid/payload/metadata/Android.bp
@@ -12,7 +12,7 @@
     rustlibs: [
         "libanyhow",
         "libmicrodroid_metadata_proto_rust",
-        "libprotobuf",
+        "libprotobuf_deprecated",
     ],
     apex_available: [
         "com.android.virt",