[recipes] Remove build environment vars from default_env

infra/bots/recipes/swarm_test.expected/big_issue_number.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
       "[SLAVE_BUILD]\\skia\\infra\\bots\\assets\\skp\\VERSION",
       "/path/to/tmp/"
     ],
     "name": "Get downloaded SKP VERSION"
@@ skipping 98 matching lines @@
     "cmd": [
       "python",
       "-u",
       "\nimport contextlib\nimport math\nimport socket\nimport sys\nimport time\nimport urllib2\n\nHASHES_URL = 'https://gold.skia.org/_/hashes'\nRETRIES = 5\nTIMEOUT = 60\nWAIT_BASE = 15\n\nsocket.setdefaulttimeout(TIMEOUT)\nfor retry in range(RETRIES):\n  try:\n    with contextlib.closing(\n        urllib2.urlopen(HASHES_URL, timeout=TIMEOUT)) as w:\n      hashes = w.read()\n      with open(sys.argv[1], 'w') as f:\n        f.write(hashes)\n        break\n  except Exception as e:\n    print 'Failed to get uninteresting hashes from %s:' % HASHES_URL\n    print e\n    if retry == RETRIES:\n      raise\n    waittime = WAIT_BASE * math.pow(2, retry)\n    print 'Retry in %d seconds.' % waittime\n    time.sleep(waittime)\n",
       "[SLAVE_BUILD]\\tmp\\uninteresting_hashes.txt"
     ],
     "cwd": "[SLAVE_BUILD]\\skia",
     "env": {
       "BUILDTYPE": "Release_x64",
       "CHROME_HEADLESS": "1",
-      "GYP_DEFINES": "qt_sdk=C:/Qt/Qt5.1.0/5.1.0/msvc2012_64/ skia_arch_type=x86_64 skia_gpu=0 skia_warnings_as_errors=0 skia_win_debuggers_path=c:/DbgHelp",
       "SKIA_OUT": "[SLAVE_BUILD]\\out"
     },
     "name": "get uninteresting hashes",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import contextlib@@@",
       "@@@STEP_LOG_LINE@python.inline@import math@@@",
       "@@@STEP_LOG_LINE@python.inline@import socket@@@",
       "@@@STEP_LOG_LINE@python.inline@import sys@@@",
       "@@@STEP_LOG_LINE@python.inline@import time@@@",
@@ skipping 323 matching lines @@
       "image-cacherator-from-ctable",
       "serialize-8888",
       "gm",
       "_",
       "image-cacherator-from-ctable",
       "--noRAW_threading"
     ],
     "env": {
       "BUILDTYPE": "Release_x64",
       "CHROME_HEADLESS": "1",
-      "GYP_DEFINES": "qt_sdk=C:/Qt/Qt5.1.0/5.1.0/msvc2012_64/ skia_arch_type=x86_64 skia_gpu=0 skia_warnings_as_errors=0 skia_win_debuggers_path=c:/DbgHelp",
       "SKIA_OUT": "[SLAVE_BUILD]\\out"
     },
     "name": "dm"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]