Remove Win10 Quadro P400 bot.

This is now redundant with "Win10 Release (NVIDIA)". The hardware will
be put in the Swarming pool to aid that bot.

BUG=786737
TBR=jmadill@chromium.org
NOTRY=true

Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I5054e85ff952d1b7e66914be5c2cd067f60621ef
Reviewed-on: https://chromium-review.googlesource.com/831333
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524574}

content/test/gpu/generate_buildbot_json.py

@@ -402,19 +402,6 @@ FYI_WATERFALL = {
       'swarming': True,
       'os_type': 'win',
     },
-    'Win10 Release (NVIDIA Quadro P400)': {
-      'swarming_dimensions': [
-        {
-          'gpu': '10de:1cb3',
-          'os': 'Windows-10'
-        },
-      ],
-      'build_config': 'Release',
-      # This bot is a one-off and doesn't have similar slaves in the
-      # swarming pool.
-      'swarming': False,
-      'os_type': 'win',
-    },
     'Win7 x64 Release (NVIDIA)': {
       'swarming_dimensions': [
         {