Clean up rust_test_host TEST_MAPPING after default update am: b92a85ff64

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/bencher/+/1582326

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I837d61a4a4430dcfeef9e934e5cceeb81cafacd7
diff --git a/TEST_MAPPING b/TEST_MAPPING
index c2be43e..689a71b 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -2,10 +2,6 @@
 {
   "presubmit": [
     {
-      "host": true,
-      "name": "bencher_host_test_lib"
-    },
-    {
       "name": "bencher_device_test_lib"
     }
   ]