TEST_MAPPING: Move SonivoxTest to presubmit

Bug: 304383609
Change-Id: Id6c035b98433d4354a1fc8380ec267485d4f20f3
Test: Treehugger
diff --git a/TEST_MAPPING b/TEST_MAPPING
index 2dfb19b..93cdbe8 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -1,5 +1,5 @@
 {
-    "postsubmit": [
+    "presubmit": [
         { "name": "SonivoxTest" }
     ]
 }