V8: Remove deprecated test-runner flag

scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux___debug.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::git]/resources/git_setup.py",
       "--path",
       "[SLAVE_BUILD]/swarming.client",
       "--url",
       "https://chromium.googlesource.com/external/swarming.client.git"
@@ skipping 835 matching lines @@
       "--mode",
       "Debug",
       "--arch",
       "ia32",
       "--outdir",
       "out",
       "--buildbot",
       "--timeout=200",
       "--random-seed=-681703856",
       "bot_default",
-      "--ignition-turbofan",
       "--variants=ignition_turbofan",
       "--rerun-failures-count=2",
       "--swarming",
       "--json-test-results",
       "${ISOLATED_OUTDIR}/output.json"
     ],
     "name": "[trigger] Ignition - turbofan on Ubuntu-12.04",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"base_task_name\": \"Ignition - turbofan/Ubuntu-12.04/[dummy has/V8 Linux - debug/571\", @@@",
@@ skipping 169 matching lines @@
       "--mode",
       "Debug",
       "--arch",
       "ia32",
       "--outdir",
       "out",
       "--buildbot",
       "--timeout=200",
       "--random-seed=-681703856",
       "test262",
-      "--ignition-turbofan",
       "--download-data",
       "--variants=ignition_turbofan",
       "--rerun-failures-count=2",
       "--swarming",
       "--json-test-results",
       "${ISOLATED_OUTDIR}/output.json"
     ],
     "name": "[trigger] Test262 - ignition - turbofan on Ubuntu-12.04",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
@@ skipping 2301 matching lines @@
       "@@@STEP_LOG_LINE@durations@Duration: 00:00:101@@@",
       "@@@STEP_LOG_END@durations@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]