Disable flaky abstract_mcts_ai_test (#5904)

MCTS is not currently in use. Mark the test as manual to exclude it
from normal test runs.

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

src/test/cpp/net/eagle0/common/mcts/BUILD.bazel

@@ -15,11 +15,13 @@ cc_library(
 )
 
 # Test for AbstractMCTSAI algorithm
+# Disabled: MCTS is not currently in use
 cc_test(
     name = "abstract_mcts_ai_test",
     srcs = ["AbstractMCTSAI_test.cpp"],
     copts = TEST_COPTS,
     linkstatic = True,
+    tags = ["manual"],
     deps = [
         ":mock_tictactoe",
         "//src/main/cpp/net/eagle0/common/mcts/abstract:abstract_mcts_ai",
@@ -61,7 +63,6 @@ cc_test(
 test_suite(
     name = "all_abstract_tests",
     tests = [
-        ":abstract_mcts_ai_test",
         ":mcts_integration_test",
         ":mcts_node_test",
     ],