Add shards to fix linux-lacros-asan-lsan-rel builder

More tests were added to the test suite and caused timeout.
https://ci.chromium.org/ui/p/chromium/builders/ci/linux-lacros-asan-lsan-rel/5022/overview

Bug: 1449988
Change-Id: I03f854e411ab03698c366f426d65c0b86e7b0dc2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4576805
Reviewed-by: Brian Sheedy <[email protected]>
Commit-Queue: Sven Zheng <[email protected]>
Commit-Queue: Brian Sheedy <[email protected]>
Auto-Submit: Sven Zheng <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1151310}
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index a70c010..fb49113 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -2927,6 +2927,15 @@
       },
     },
   },
+  'lacros_chrome_browsertests_run_in_series': {
+    'modifications': {
+      'linux-lacros-asan-lsan-rel': {
+        'swarming': {
+          'shards': 5,
+        },
+      },
+    },
+  },
   'leveldb_unittests': {
     'remove_from': [
       # TODO(https://crbug.com/1432753): Runs too slowly in this configuration.