Disable svgs on nanobench when running on Valgrind

infra/bots/recipes/swarm_perf.expected/recipe_with_gerrit_patch.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport sys, os\npath = sys.argv[1]\nmode = int(sys.argv[2])\nif not os.path.isdir(path):\n  if os.path.exists(path):\n    print \"%s exists but is not a dir\" % path\n    sys.exit(1)\n  os.makedirs(path, mode)\n",
       "[SLAVE_BUILD]/tmp",
       "511"
     ],
     "name": "makedirs tmp_dir",
@@ skipping 78 matching lines @@
       "--track-origins=yes",
       "--error-exitcode=1",
       "--num-callers=40",
       "--suppressions=[SLAVE_BUILD]/skia/tools/valgrind.supp",
       "[SLAVE_BUILD]/out/Release/nanobench",
       "--undefok",
       "-i",
       "[SLAVE_BUILD]/skia/resources",
       "--skps",
       "[SLAVE_BUILD]/skp",
-      "--svgs",
-      "[SLAVE_BUILD]/svg",
       "--images",
       "[SLAVE_BUILD]/skimage/nanobench",
       "--nocpu",
       "--pre_log",
       "--images",
       "--gpuStatsDump",
       "true",
       "--scales",
       "1.0",
       "1.1",
@@ skipping 53 matching lines @@
       "--track-origins=yes",
       "--error-exitcode=1",
       "--num-callers=40",
       "--suppressions=[SLAVE_BUILD]/skia/tools/valgrind.supp",
       "[SLAVE_BUILD]/out/Release/nanobench",
       "--undefok",
       "-i",
       "[SLAVE_BUILD]/skia/resources",
       "--skps",
       "[SLAVE_BUILD]/skp",
-      "--svgs",
-      "[SLAVE_BUILD]/svg",
       "--images",
       "[SLAVE_BUILD]/skimage/nanobench",
       "--nocpu",
       "--pre_log",
       "--images",
       "--gpuStatsDump",
       "true",
       "--scales",
       "1.0",
       "1.1",
@@ skipping 46 matching lines @@
       "SKIA_OUT": "[SLAVE_BUILD]/out"
     },
     "name": "nanobench --abandonGpuContext"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]