Add option for test discovery info mode

Add a command line option to enable test discovery info mode, where
enabling it will cause test discovery to run and report results but not
actually affect the build. This is useful for rolling out to new targets
without immediately enabling test discovery mode.

Test: atest build_test_suites_test
Bug: 388833029
Change-Id: I8baf73e6353e4c3d7d6836c4f9823341a7f8b5dd
diff --git a/ci/build_test_suites.py b/ci/build_test_suites.py
index cdcba5a..0cae816 100644
--- a/ci/build_test_suites.py
+++ b/ci/build_test_suites.py
@@ -84,14 +84,14 @@
     packaging_commands_getters = []
     # In order to roll optimizations out differently between test suites and
     # device builds, we have separate flags.
-    enable_discovery = ('test_suites_zip_test_discovery'
+    enable_discovery = (('test_suites_zip_test_discovery'
         in self.build_context.enabled_build_features
         and not self.args.device_build
     ) or (
         'device_zip_test_discovery'
         in self.build_context.enabled_build_features
         and self.args.device_build
-    )
+    )) and not self.args.test_discovery_info_mode
     logging.info(f'Discovery mode is enabled= {enable_discovery}')
     preliminary_build_targets = self._collect_preliminary_build_targets(enable_discovery)
 
@@ -252,6 +252,11 @@
       action='store_true',
       help='Flag to indicate running a device build.',
   )
+  argparser.add_argument(
+      '--test_discovery_info_mode',
+      action='store_true',
+      help='Flag to enable running test discovery in info only mode.',
+  )
 
   return argparser.parse_args(argv)