Don't run ComposHostTestCases in presubmit

They're flaky on cuttlefish. Move to postsubmit instead.

Bug: 264496291
Test: N/A
Change-Id: I19b0357632be5a89e096fd1d9ce8d47dd865d245
diff --git a/TEST_MAPPING b/TEST_MAPPING
index efcdb36..4148002 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -19,7 +19,9 @@
         },
         {
             "name": "MicrodroidHostTestCases"
-        },
+        }
+    ],
+    "avf-postsubmit": [
         {
             "name": "ComposHostTestCases"
         }