[test] Add avx2 bot to CQ.

BUG=chromium:478460
LOG=n
NOTRY=true
TBR=bmeurer@chromium.org, mvstanton@chromium.org

Review URL: https://codereview.chromium.org/1107973007

Cr-Commit-Position: refs/heads/master@{#28149}

PRESUBMIT.py

@@ -249,6 +249,7 @@ def GetPreferredTryMasters(project, change):
       'v8_linux_gcc_compile_rel': set(['defaulttests']),
       'v8_linux64_rel': set(['defaulttests']),
       'v8_linux64_asan_rel': set(['defaulttests']),
+      'v8_linux64_avx2_rel': set(['defaulttests']),
       'v8_win_rel': set(['defaulttests']),
       'v8_win_compile_dbg': set(['defaulttests']),
       'v8_win_nosnap_shared_compile_rel': set(['defaulttests']),

testing/commit_queue/config.json

@@ -29,6 +29,9 @@
                     "v8_linux64_asan_rel": [
                         "defaulttests"
                     ],
+                    "v8_linux64_avx2_rel": [
+                        "defaulttests"
+                    ],
                     "v8_linux64_rel": [
                         "defaulttests"
                     ],