[test] Fix the noi18n trybot

This is a work-around as v8_enable_i18n_support=false does
currently not imply icu_use_data_file_flag=false. The
swarming isolator then tries to find the data file also
in builds without ICU.

Making the implication is non-trivial as icu_use_data_file_flag lives
in ICU and v8_enable_i18n_support lives in V8.

BUG=chromium:474921
NOTRY=true
TBR=petermarshall@chromium.org, vogelheim@chromium.org, jochen@chromium.org

Review-Url: https://codereview.chromium.org/2321563007
Cr-Commit-Position: refs/heads/master@{#39301}

infra/mb/mb_config.pyl

@@ -614,8 +614,8 @@
     },
 
     'v8_no_i18n': {
-      'gn_args': 'v8_enable_i18n_support=false',
-      'gyp_defines': 'v8_enable_i18n_support=0',
+      'gn_args': 'v8_enable_i18n_support=false icu_use_data_file_flag=false',
+      'gyp_defines': 'v8_enable_i18n_support=0 icu_use_data_file_flag=0',
     },
 
     'v8_enable_disassembler': {