Update slave scripts to set skia_arch_type but not skia_arch_width

scripts/slave/recipes/skia/skia.expected/Test-iOS-Clang-iPad4-GPU-SGX554-Arm7-Debug.json

 [
   {
     "cmd": [
       "git",
       "fetch"
     ],
     "cwd": "[SLAVE_BUILD]/skia",
     "name": "git fetch"
   },
   {
@@ skipping 57 matching lines @@
       "@@@SET_BUILD_PROPERTY@got_revision@164710@@@"
     ]
   },
   {
     "cmd": [
       "[SLAVE_BUILD]/skia/platform_tools/ios/bin/ios_ninja"
     ],
     "cwd": "[SLAVE_BUILD]/skia",
     "env": {
       "BUILDTYPE": "Debug",
-      "GYP_DEFINES": "skia_arch_type=arm skia_arch_width=32 skia_clang_build=1 skia_os=ios skia_warnings_as_errors=0",
+      "GYP_DEFINES": "skia_arch_type=arm skia_clang_build=1 skia_os=ios skia_warnings_as_errors=0",
       "SKIA_OUT": "[SLAVE_BUILD]/skia/out/Test-iOS-Clang-iPad4-GPU-SGX554-Arm7-Debug"
     },
     "name": "build iOSShell"
   },
   {
     "cmd": [
       "[SLAVE_BUILD]/skia/platform_tools/ios/bin/ios_install"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
@@ skipping 420 matching lines @@
       "--dummy-flags"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "BUILDTYPE": "Debug",
       "SKIA_OUT": "[SLAVE_BUILD]/skia/out/Test-iOS-Clang-iPad4-GPU-SGX554-Arm7-Debug"
     },
     "name": "nanobench"
   }
 ]