Revert of Linux MSan: enable swarming/sharding for browser_tests. (patchset #1...

Revert of Linux MSan: enable swarming/sharding for browser_tests. (patchset #1 id:1 of https://codereview.chromium.org/899283003/)

Reason for revert:
broke browser_tests

Original issue's description:
> Linux MSan: enable swarming/sharding for browser_tests.
>
> Also, try enabling swarming for base_unittests on CrOS MSan.
>
> BUG=454828
> TBR=phajdan.jr@chromium.org
>
> Committed: https://crrev.com/0f7445a90f7a8e2aa54a812d2c96654cefbd8eaf
> Cr-Commit-Position: refs/heads/master@{#314892}

TBR=phajdan.jr@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=454828

Review URL: https://codereview.chromium.org/898083003

Cr-Commit-Position: refs/heads/master@{#314949}

testing/buildbot/chromium.memory.fyi.json

@@ -4,12 +4,10 @@
       "accessibility_unittests",
       "app_list_unittests",
       "aura_unittests",
-      "base_unittests",
       {
-        "test": "browser_tests",
+        "test": "base_unittests",
         "swarming": {
-          "can_use_on_swarming_builders": true,
-          "shards": 3
+          "can_use_on_swarming_builders": true
         }
       },
       "cacheinvalidation_unittests",
@@ -78,12 +76,7 @@
       "accessibility_unittests",
       "app_list_unittests",
       "aura_unittests",
-      {
-        "test": "base_unittests",
-        "swarming": {
-          "can_use_on_swarming_builders": true
-        }
-      },
+      "base_unittests",
       "cacheinvalidation_unittests",
       "cast_unittests",
       "cc_unittests",