Revert "Add is_chrome_branded to kythe codesearch builds"

This reverts commit 5d17f9ea.

Reason for revert: breaks builds when looking for ../../chrome/app/theme/google_chrome/BRANDING

Original change's description:
> Add is_chrome_branded to kythe codesearch builds
>
> Bug: b/140589523
> Change-Id: I01e015551729dc440187735fd689486eaabd6cf8
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1838053
> Reviewed-by: Aaron Gable <agable@chromium.org>
> Commit-Queue: Anthony Polito <apolito@google.com>
> Cr-Commit-Position: refs/heads/master@{#704808}


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

TBR=agable@chromium.org

Bug: b/140589523
Change-Id: Iba284db236c97c0400adb8d0371182135227b947
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1857518Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Aaron Gable <agable@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705607}

tools/mb/mb_config.pyl

@@ -2144,15 +2144,11 @@
 
     # Settings used by the codesearch builders to generate cross-references.
     'codesearch': {
-      'gn_args': ('clang_use_chrome_plugins=false '
-                  'enable_kythe_annotations=true '
-                  'is_chrome_branded=true'),
+      'gn_args': 'clang_use_chrome_plugins=false enable_kythe_annotations=true',
       'mixins': ['goma', 'clang', 'shared', 'debug', 'minimal_symbols'],
     },
     'codesearch_release': {
-      'gn_args': ('clang_use_chrome_plugins=false '
-                  'enable_kythe_annotations=true '
-                  'is_chrome_branded=true'),
+      'gn_args': 'clang_use_chrome_plugins=false enable_kythe_annotations=true',
       'mixins': ['release', 'static', 'goma'],
     },