Add aosp_riscv64 to build_test skipped products

aosp_riscv64 isn't ready for build_test yet, it still requires
ALLOW_MISSING_DEPENDENCIES=true to build.

Bug: 250918230
Change-Id: I9151fa84bf6ad0fa67dd06d3268311ae716b5185
Test: none
diff --git a/build_test.bash b/build_test.bash
index 6f0fba7..92819a1 100755
--- a/build_test.bash
+++ b/build_test.bash
@@ -29,6 +29,9 @@
     linux_bionic
     mainline_sdk
     ndk
+
+    # New architecture bringup, fails without ALLOW_MISSING_DEPENDENCIES=true
+    aosp_riscv64
 )
 
 # To track how long we took to startup. %N isn't supported on Darwin, but