Remove hard-coded SPL from microdroid vbmeta

Since it uses hashtree descriptor root digest to verify microdroid vendor
partition, microdroid vbmeta doesn't need to put hard-coded value.

Bug: 312809093
Test: adb shell /apex/com.android.virt/bin/vm run-microdroid --vendor /vendor/etc/avf/microdroid/microdroid_vendor.img --protected
Test: adb shell /apex/com.android.virt/bin/vm run-microdroid --vendor /vendor/etc/avf/microdroid/microdroid_vendor.img
Test: atest MicrodroidTests#bootsWithVendorPartition
Change-Id: Ifc0020f5f8919ad8c6066304ec3bf5b4da4834cd
diff --git a/microdroid/Android.bp b/microdroid/Android.bp
index f98f3af..ae89f79 100644
--- a/microdroid/Android.bp
+++ b/microdroid/Android.bp
@@ -394,16 +394,6 @@
             partitions: ["microdroid_vendor"],
         },
     },
-    // TODO(b/312809093): Remove hard-coded property after figuring out the
-    // long-term solution for microdroid vendor partition SPL. The hard-coded
-    // value is the minimum value of SPL that microdroid vendor partition will
-    // have. It's for passing the check 'IsStandaloneImageRollback'.
-    avb_properties: [
-        {
-            key: "com.android.build.microdroid-vendor.security_patch",
-            value: "2023-12-05",
-        },
-    ],
 }
 
 prebuilt_etc {