Revive linux_chromium_ubsan_rel_ng mb config.

Bug: 855269
Change-Id: I8ab4534f2ede8c0b8d2f3348309046ee0de9d164
Reviewed-on: https://chromium-review.googlesource.com/1112043Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569910}

tools/mb/mb_config.pyl

@@ -627,6 +627,7 @@
 
       'linux_chromium_rel_ng': 'gpu_tests_release_trybot_no_symbols',
       'linux_chromium_tsan_rel_ng': 'tsan_disable_nacl_release_trybot',
+      'linux_chromium_ubsan_rel_ng': 'ubsan_vptr_release_trybot',
       'linux_layout_tests_layout_ng': 'release_trybot',
       'linux_layout_tests_root_layer_scrolls': 'release_trybot',
       'linux_layout_tests_slimming_paint_v2': 'release_trybot',
@@ -1608,6 +1609,10 @@
       'ubsan_vptr', 'ubsan_no_recover_hack', 'release_bot',
     ],
 
+    'ubsan_vptr_release_trybot': [
+      'ubsan_vptr', 'ubsan_no_recover_hack', 'release_trybot',
+    ],
+
     'v8_future_debug_bot': [
       'v8_future', 'debug_bot',
     ],