iOS: Cleanup buildbot JSON files + bump iOS version to 10.0

webrtc/build/ios/tryserver.webrtc/ios64_gn_dbg.json

Index: webrtc/build/ios/tryserver.webrtc/ios64_gn_dbg.json
diff --git a/webrtc/build/ios/tryserver.webrtc/ios64_gn_dbg.json b/webrtc/build/ios/tryserver.webrtc/ios64_gn_dbg.json
deleted file mode 100644
index af16ffa489f4e1d517a21648852478c8b75df085..0000000000000000000000000000000000000000
--- a/webrtc/build/ios/tryserver.webrtc/ios64_gn_dbg.json
+++ /dev/null
@@ -1,35 +0,0 @@
-{
-  "owners": [
-    "kjellander"
-  ],
-  "comments": [
-    "GN + Ninja builder.",
-    "GYP_DEFINES and gn_args in this file are only used during runhooks; ",
-    "webrtc/build/mb_config.pyl decides the generated projects that are compiled."
-  ],
-  "xcode version": "8.0",
-  "GYP_DEFINES": [
-    "use_goma=1",
-    "gomadir=$(goma_dir)",
-    "chromium_ios_signing=0",
-    "component=static_library",
-    "target_arch=arm64"
-  ],
-  "gn_args": [
-    "is_debug=true",
-    "target_os=\"ios\"",
-    "ios_enable_code_signing=false",
-    "is_component_build=false",
-    "use_goma=true",
-    "goma_dir=\"$(goma_dir)\"",
-    "target_cpu=\"arm64\""
-  ],
-  "mb_type": "gyp",
-  "use_analyze": false,
-  "compiler": "ninja",
-  "additional_compile_targets": [ "all" ],
-  "configuration": "Debug",
-  "sdk": "iphoneos9.0",
-  "tests": [
-  ]
-}