Clean up rust_test_host TEST_MAPPING after default update am: 9d0886bb68

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/fallible-streaming-iterator/+/1590472

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I57f984cbc5d27d55a44dd2337541560bb69f7244
diff --git a/TEST_MAPPING b/TEST_MAPPING
index 1771bdd..3b7bc44 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -2,10 +2,6 @@
 {
   "presubmit": [
     {
-      "host": true,
-      "name": "fallible-streaming-iterator_host_test_src_lib"
-    },
-    {
       "name": "fallible-streaming-iterator_device_test_src_lib"
     }
   ]