Add idsig test to presubmit

The lack of this test in presubmit resulted in breakage so make sure
that doesn't happen again.

Bug: 248068872
Test: presubmit
Change-Id: Ia633e30a97b2b9f68648fd31369d0da3a8320d0a
diff --git a/TEST_MAPPING b/TEST_MAPPING
index 11648c4..8cce099 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -47,6 +47,9 @@
       "path": "packages/modules/Virtualization/libs/apkverify"
     },
     {
+      "path": "packages/modules/Virtualization/libs/idsig"
+    },
+    {
       "path": "packages/modules/Virtualization/libs/vbmeta"
     },
     {