[CQ] Add linux64 debug trybot to CQ experiment

It'll replace the linux32 debug trybot in CQ soon when it's confirmed stable.

This also adds the corresponding MB config.

NOTRY=true
TBR=sergiyb@chromium.org

Change-Id: I99464d7d2d776390e59c48f0f65daa213a14f0f7
Reviewed-on: https://chromium-review.googlesource.com/1009746Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52564}

infra/config/cq.cfg

@@ -30,6 +30,10 @@ verifiers {
         name: "v8_linux64_asan_rel_ng_triggered"
         triggered_by: "v8_linux64_asan_rel_ng"
       }
+      builders {
+        name: "v8_linux64_dbg_ng"
+        experiment_percentage: 100
+      }
       builders { name: "v8_linux64_gcc_compile_dbg" }
       builders { name: "v8_linux64_jumbo_compile_rel" }
       builders { name: "v8_linux64_rel_ng" }

infra/mb/mb_config.pyl

@@ -201,6 +201,7 @@
       'v8_linux_gcc_compile_rel': 'release_x86_gcc_minimal_symbols',
       'v8_linux_gcc_rel': 'release_x86_gcc_minimal_symbols',
       'v8_linux_shared_compile_rel': 'release_x86_shared_verify_heap',
+      'v8_linux64_dbg_ng': 'debug_x64_trybot',
       'v8_linux64_gcc_compile_dbg': 'debug_x64_gcc',
       'v8_linux64_fyi_rel_ng': 'release_x64_test_features_trybot',
       'v8_linux64_rel_ng': 'release_x64_test_features_trybot',