Enable post-compile test isolation for all CI builders.

scripts/slave/recipes/chromium.expected/full_chromium_linux_Linux_Builder.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "chromium.linux",
       "--builder",
       "Linux Builder",
@@ skipping 190 matching lines @@
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/tools/swarming_client/isolate.py",
       "batcharchive",
       "--dump-json",
       "/path/to/tmp/json",
       "--isolate-server",
       "https://isolateserver.appspot.com",
+      "--verbose",
       "[SLAVE_BUILD]/src/out/Release/browser_tests.isolated.gen.json"
     ],
     "name": "isolate tests",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"browser_tests\": \"[dummy hash for browser_tests]\"@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@",
       "@@@SET_BUILD_PROPERTY@swarm_hashes@{\"browser_tests\": \"[dummy hash for browser_tests]\"}@@@"
     ]
@@ skipping 29 matching lines @@
       "--build_revision",
       "170242",
       "--factory-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"Linux Builder\", \"buildnumber\": 571, \"mastername\": \"chromium.linux\", \"parent_buildername\": null, \"recipe\": \"chromium\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}",
       "--build-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"Linux Builder\", \"buildnumber\": 571, \"mastername\": \"chromium.linux\", \"parent_buildername\": null, \"recipe\": \"chromium\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}"
     ],
     "name": "package build"
   }
 ]