Revert "Fix iOS sim bot to for the new Chromium roll"

This reverts commit 7ca630f8dd0c1c8179a635660c0265bb5f4ea179.

Reason for revert: The new version of clang should have fixed the problem.

Original change's description:
> Fix iOS sim bot to for the new Chromium roll
>
> Bug: b/199044368, chromium:1249456
> Change-Id: I0d91abca55618d87dc8366315182729e2a2b1016
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/231954
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Andrey Logvin <landrey@webrtc.org>
> Commit-Queue: Artem Titov <titovartem@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#34992}

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: b/199044368, chromium:1249456
Change-Id: I67d96129d5f3a8159412b3755994b542633e2816
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/232333
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35069}
diff --git a/tools_webrtc/mb/mb_config.pyl b/tools_webrtc/mb/mb_config.pyl
index 4b85fc7..e5ea769 100644
--- a/tools_webrtc/mb/mb_config.pyl
+++ b/tools_webrtc/mb/mb_config.pyl
@@ -400,7 +400,6 @@
     ],
     'ios_debug_bot_x64': [
       'ios', 'debug_bot', 'x64', 'ios_use_goma_rbe', 'xctest',
-      'ios_old_os_support',
     ],
 
     # More configs
@@ -500,11 +499,6 @@
       'gn_args': 'target_os="ios"',
     },
 
-    # TODO(crbug.com/1249456): Remove use_lld=false
-    'ios_old_os_support' :{
-      'gn_args': 'use_lld=false',
-    },
-
     'no_goma': {
       'gn_args': 'use_goma=false',
     },