Clean up TEST_MAPPING after default update

cc_test_host doesn't need TEST_MAPPING config anymore to run in
presubmit. (go/a-unit-tests)

Change-Id: Ia07ea311cf6febc2f937ab14966ad21dfd623c69
Test: presubmit
Bug: 178646865
diff --git a/TEST_MAPPING b/TEST_MAPPING
index a304582..1237285 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -5,10 +5,6 @@
     },
     {
       "name": "recovery_unit_test"
-    },
-    {
-      "name": "recovery_host_test",
-      "host": true
     }
   ]
 }