auto_roll.py: use LUCI for the optional GPU tests on Mac

BUG=chromium:815092

Change-Id: Iec8207dddc56bbcc06ffe7755fc3dc7120bc4368
Reviewed-on: https://chromium-review.googlesource.com/971355Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52084}

tools/release/auto_roll.py

@@ -20,7 +20,7 @@ Please close rolling in case of a roll revert:
 https://v8-roll.appspot.com/
 This only works with a Google account.
 
-CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;luci.chromium.try:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel""")
+CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel""")
 
 class Preparation(Step):
   MESSAGE = "Preparation."

tools/release/test_scripts.py

@@ -1037,7 +1037,7 @@ Please close rolling in case of a roll revert:
 https://v8-roll.appspot.com/
 This only works with a Google account.
 
-CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;luci.chromium.try:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
+CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
 
 TBR=reviewer@chromium.org"""