Remove unnecessary modifications to telemetry_unittest suite

Bug: 753495
Change-Id: I6e23e7b536b52c05070661869fb67ea8d04bc9d0
Reviewed-on: https://chromium-review.googlesource.com/850713Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#527026}

testing/buildbot/test_suite_exceptions.pyl

@@ -3486,45 +3486,6 @@
   },
   'telemetry_unittests': {
     'modifications': {
-      'Linux Tests SANDBOX': {
-        'args': [
-          '--jobs=1',
-        ],
-        'swarming': {
-          'shards': 4,
-        },
-      },
-      'Linux Tests': {
-        'args': [
-          '--jobs=1',
-        ],
-        'swarming': {
-          'shards': 4,
-        },
-      },
-      'Linux Tests (dbg)(1)': {
-        'args': [
-          '--jobs=1',
-        ],
-        'swarming': {
-          'shards': 4,
-        },
-      },
-      'Linux Tests (dbg)(1)(32)': {
-        'args': [
-          '--jobs=1',
-        ],
-        'swarming': {
-          'shards': 4,
-        },
-      },
-      # TODO(kbr): this looks like an accident while removing parallelism from
-      # telemetry_perf_unittests.
-      'Mac10.12 Tests': {
-        'args': [
-          '--jobs=1',
-        ],
-      },
       'Out of Process Profiling Mac': {
         'swarming': {
           'shards': 2,