Remove microdroid build of keystore2

keystore2 has been removed from microdroid so the build variant is no
longer needed.

Bug: 215747811
Test: atest MicrodroidTests
Change-Id: I46395d04535a3084e995324445e6b52bef4d8154
diff --git a/keystore2/Android.bp b/keystore2/Android.bp
index 520237a..c383f4f 100644
--- a/keystore2/Android.bp
+++ b/keystore2/Android.bp
@@ -167,18 +167,3 @@
         "librusqlite",
     ],
 }
-
-// Variant of keystore2 for use in microdroid. It doesn't depend on the ICU-enabled sqlite.
-// This can be used also in Android, but we choose not to because it will bring two
-// variants of sqlite to the system causing more RAM usage and CPU cycles when loading.
-rust_binary {
-    name: "keystore2_microdroid",
-    stem: "keystore2",
-    defaults: ["keystore2_defaults"],
-    rustlibs: [
-        "libkeystore2_noicu",
-        "liblegacykeystore-rust_noicu",
-        "librusqlite_noicu",
-    ],
-    installable: false, // don't install this to Android
-}