weblayer, skew tests: Remove goma mixin from mb_config.pyl used to

compile skew test binaries

Currently there is a freeze in increasing GOMA usage. So I had to
remove goma compilation from the skew test refresher recipe,
CL crrev.com/i/3462616.

Bug: 1147459, 1099017, 1041619, 1156861
Change-Id: Ibdbc2dfb7364dd7ed0083a76bf041a48de7be392
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2590372Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Rakib Hasan <rmhasan@google.com>
Cr-Commit-Position: refs/heads/master@{#836892}

weblayer/browser/android/javatests/skew/mb_config.pyl

@@ -67,7 +67,7 @@
     },
 
     'release_bot': {
-      'mixins': ['release', 'static', 'goma'],
+      'mixins': ['release', 'static'],
     },
 
     'static': {