[build][test] Add MB and test configs for tsan isolates trybot

This also removes the config for a non-existing builder.

TBR=sergiyb@chromium.org
NOTRY=true

Bug: v8:8009
Change-Id: Ic6d65bce46db9807ffcbeb51d507b51ca5311cfe
Reviewed-on: https://chromium-review.googlesource.com/1161802
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54885}

infra/mb/mb_config.pyl

@@ -228,7 +228,7 @@
       'v8_linux64_jumbo_compile_rel': 'release_x64_jumbo_trybot',
       'v8_linux64_jumbo_limited_compile_rel': 'release_x64_jumbo_limited_trybot',
       'v8_linux64_tsan_rel': 'release_x64_tsan_minimal_symbols',
-      'v8_linux64_tsan_concurrent_marking_rel_ng':
+      'v8_linux64_tsan_isolates_rel_ng':
           'release_x64_tsan_minimal_symbols',
       'v8_linux64_ubsan_rel_ng': 'release_x64_ubsan_vptr_minimal_symbols',
       # TODO(machenbach): Remove after switching to x64 on infra side.

infra/testing/builders.pyl

@@ -218,6 +218,11 @@
       {'name': 'v8testing', 'variant': 'slow_path'},
     ],
   },
+  'v8_linux64_tsan_isolates_rel_ng_triggered': {
+    'tests': [
+      {'name': 'v8testing', 'test_args': ['--isolates'], 'shards': 7},
+    ],
+  },
   'v8_linux64_ubsan_rel_ng_triggered': {
     'tests': [
       {'name': 'v8testing', 'shards': 2},