mb: Ignore Widevine signing failure on ToTMacOfficial

This is a follow up from previous CL [1] to fix more bots.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/2415369

Bug: 1127616
Change-Id: Idaa97e3203da054d62a94b3ad59fb6fd8acab2f5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2414570Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: Michael Moss <mmoss@chromium.org>
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808075}

tools/mb/mb_config.pyl

@@ -169,7 +169,7 @@
       'ToTLinuxThinLTO': 'clang_tot_release_minimal_symbols_thin_lto_opt_static',
       'ToTLinuxUBSanVptr': 'clang_tot_ubsan_no_recover_hack_static_release',
       'ToTMac': 'clang_tot_minimal_symbols_shared_release',
-      'ToTMacOfficial': 'clang_tot_official',
+      'ToTMacOfficial': 'mac_clang_tot_official',
       'ToTMacCoverage': 'clang_tot_coverage_minimal_symbols_release',
       'ToTMac (dbg)': 'clang_tot_shared_debug',
       'ToTMacASan': 'asan_disable_nacl_clang_tot_minimal_symbols_static_release',
@@ -2137,6 +2137,9 @@
       'release_trybot', 'arm64',
     ],
 
+    'mac_clang_tot_official': [
+      'clang_tot', 'official', 'no_widevine_cdm_host_verification',
+    ],
 
     'msan_no_origins_release_bot': [
       'msan_no_origins', 'release_bot',