AOSP/Messaging - Remove TEST_MAPPING because presubmit tests fail on build_target: aosp_cf_x86_phone-userdebug

BUG: 126516784

Test: No impact. TEST_MAPPING wasn't enabled before, thus removing the file shouldn't have an impact.
Change-Id: Ib206cb6d921b59a032e6557352c6961310b08272
diff --git a/TEST_MAPPING b/TEST_MAPPING
deleted file mode 100644
index 55688d5..0000000
--- a/TEST_MAPPING
+++ /dev/null
@@ -1,7 +0,0 @@
-{
-  "presubmit": [
-    {
-      "name": "messagingtests"
-    }
-  ]
-}