Revert "Move fstab.microdroid to /system partition"

Revert submission 2625691

Reason for revert: b/287283650

Reverted changes: /q/submissionid:2625691

Change-Id: Ib6dda75a76131288631f8926cc6e37749aef6ec6
diff --git a/microdroid/initrd/Android.bp b/microdroid/initrd/Android.bp
index 699a28a..22a06e1 100644
--- a/microdroid/initrd/Android.bp
+++ b/microdroid/initrd/Android.bp
@@ -32,7 +32,7 @@
     name: "microdroid_initrd_gen",
     srcs: [
         ":microdroid_ramdisk",
-        ":microdroid_fstab_ramdisk",
+        ":microdroid_vendor_ramdisk",
     ],
     out: ["microdroid_initrd.img"],
     cmd: "cat $(in) > $(out)",