Move ComposHostTestCases to postsubmit, since it has a high failure rate on cf in presubmit.

Bug: 264496291
Change-Id: I70dfc635de37adc8f9107466e06a887da02f0797

TEST_MAPPING

@@ -3,9 +3,6 @@
     {
       "name": "MicrodroidHostTestCases"
     },
-    {
-      "name": "ComposHostTestCases"
-    },
     {
       "name": "MicrodroidTestApp"
     },
@@ -35,6 +32,9 @@
     {
       "name": "ComposBenchmarkApp"
     },
+    {
+      "name": "ComposHostTestCases"
+    },
     {
       "name": "AVFHostTestCases"
     }