MB: Fix incorrect iOS builder names.

In https://codereview.webrtc.org/2239643002/ MB was turned on
for the iOS GYP bots. This exposed an incorrect config for the
iOS simulator bots in client.webrtc.

BUG=589510
NOTRY=True

Review-Url: https://codereview.webrtc.org/2245393003
Cr-Commit-Position: refs/heads/master@{#13778}
diff --git a/webrtc/build/mb_config.pyl b/webrtc/build/mb_config.pyl
index 99e1433..b796089 100644
--- a/webrtc/build/mb_config.pyl
+++ b/webrtc/build/mb_config.pyl
@@ -24,8 +24,8 @@
       'iOS32 Release': 'ios_gyp_release_bot_arm_device',
       'iOS64 Debug': 'ios_gyp_debug_static_bot_arm64_device',
       'iOS64 Release': 'ios_gyp_release_bot_arm64_device',
-      'iOS32 Debug Simulator': 'ios_gyp_debug_static_bot_x86',
-      'iOS64 Debug Simulator': 'ios_gyp_debug_static_bot_x64',
+      'iOS32 Simulator Debug': 'ios_gyp_debug_static_bot_x86',
+      'iOS64 Simulator Debug': 'ios_gyp_debug_static_bot_x64',
       'iOS64 Debug (GN)': 'ios_gn_debug_static_bot_arm64_device',
       'iOS64 Release (GN)': 'ios_gn_release_bot_arm64_device',