[Swarming] Switch off test isolation check by default.

build/standalone.gypi

Index: build/standalone.gypi
diff --git a/build/standalone.gypi b/build/standalone.gypi
index e4d1b4bd582f98562acfa0291ffbfce7721bab45..3a9e637da061e5328514485113b43da0d220138c 100644
--- a/build/standalone.gypi
+++ b/build/standalone.gypi
@@ -113,6 +113,8 @@
       # Check if valgrind directories are present.
       'has_valgrind%': '<!pymod_do_main(has_valgrind)',
 
+      'test_isolation_mode%': 'noop',
+
       'conditions': [
         # Set default gomadir.
         ['OS=="win"', {
@@ -136,14 +138,6 @@
         }, {
           'linux_use_bundled_gold%': 0,
         }],
-
-        # TODO(machenbach): Remove the conditions as more configurations are
-        # supported.
-        ['OS=="linux" or OS=="win"', {
-          'test_isolation_mode%': 'check',
-        }, {
-          'test_isolation_mode%': 'noop',
-        }],
       ],
     },
     'base_dir%': '<(base_dir)',