Include TEST_MAPPING in ./libs/devicemapper

This ensures libdm_rust.test are part of avf-presubmit group.

Bug: 250880499
Test: Monitor TH
Change-Id: I9ba0320f99d4f985c8d217423daa45d624baff34
diff --git a/TEST_MAPPING b/TEST_MAPPING
index 11648c4..93bc2bb 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -47,6 +47,9 @@
       "path": "packages/modules/Virtualization/libs/apkverify"
     },
     {
+      "path": "packages/modules/Virtualization/libs/devicemapper"
+    },
+    {
       "path": "packages/modules/Virtualization/libs/vbmeta"
     },
     {