Fix lunch choices for git_main

We add "trunk_staging-" for all COMMON_LUNCH_CHOICES so they are
valid in the trunk stable setup.

Bug: 307738446
Test: lunch
Change-Id: Iae9d3de2ee9b5ca7b15c4b78abc548ea434e575e
diff --git a/AndroidProducts.mk b/AndroidProducts.mk
index c502774..3ba8267 100644
--- a/AndroidProducts.mk
+++ b/AndroidProducts.mk
@@ -18,4 +18,4 @@
     $(LOCAL_DIR)/uml.mk
 
 COMMON_LUNCH_CHOICES := \
-    uml-userdebug
+    uml-trunk_staging-userdebug