build: Default test modules to null-suite

The LOCAL_COMPATIBILITY_SUITE tag is used to package tests and
auto-generate test configs for use in the test infrastructure
and locally by atest.

Rather than update hundreds of makefiles across the tree, this
change adds significant atest support to many unittests.

Bug: 73000943, 72969679, 71510529
Test: `atest NotificationStressTests` works as expected.
Change-Id: I1b0a779b8366aee4b4df98181267f72fcb68916a
diff --git a/core/base_rules.mk b/core/base_rules.mk
index 3ff3bd3..9d7daa0 100644
--- a/core/base_rules.mk
+++ b/core/base_rules.mk
@@ -494,6 +494,17 @@
 endif
 endif
 
+# For modules tagged as tests but lacking a suite tag, set null-suite as the default.
+# We only support adding a default suite to native tests, native benchmarks, and instrumentation tests.
+# This is because they are the only tests we currently auto-generate test configs for.
+ifneq ($(filter $(my_module_tags),tests),)
+ifndef LOCAL_COMPATIBILITY_SUITE
+ifneq ($(filter NATIVE_TESTS NATIVE_BENCHMARK APPS, $(LOCAL_MODULE_CLASS)),)
+LOCAL_COMPATIBILITY_SUITE := null-suite
+endif
+endif
+endif
+
 ###########################################################
 ## Compatibility suite files.
 ###########################################################