Update bsdiff_unittest to really work host-side

bsdiff_unittest is marked host_supported:true but use
a AndroidTest.xml config that can only work for device.

Deleting the explict config to rely on the auto-gen ones.
Adding unit_tests:true to run in presubmit

Change-Id: Ia3a23149ccdc2efa2c880436e30fcff4acf9ddd9
Test: presubmit, atest bsdiff_unittest --host
Bug: 179092189
diff --git a/Android.bp b/Android.bp
index 0330a32..ee6dc4f 100644
--- a/Android.bp
+++ b/Android.bp
@@ -163,4 +163,7 @@
             cflags: ["-DBSDIFF_TARGET_UNITTEST"],
         },
     },
+    test_options: {
+        unit_test: true,
+    },
 }