Add a repo hook to validate TEST_MAPPING file.

Bug: 77805721
Test: repo upload a bad TEST_MAPPING file, trigger the repo hook
Change-Id: I6ccd5ec95f33d6cc2357bf5d9a9556af4a66caf6
diff --git a/GLOBAL-PREUPLOAD.cfg b/GLOBAL-PREUPLOAD.cfg
index b98a673..34044f2 100644
--- a/GLOBAL-PREUPLOAD.cfg
+++ b/GLOBAL-PREUPLOAD.cfg
@@ -7,6 +7,7 @@
 
 [Builtin Hooks]
 commit_msg_test_field = true
+android_test_mapping_format = true
 
 [Tool Paths]
 clang-format = ${REPO_ROOT}/prebuilts/clang/host/${BUILD_OS}/clang-stable/bin/clang-format