[M101]Increase shards of interactive_ui_tests on linux-chromeos-dbg

The shard run time were close to the time out limit of 1h, causing
frequent failures.

(cherry picked from commit 582a15d)

Bug: 1311132
Change-Id: I7249cf2175c17b6ce3824a3f2b08673328b70574
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3563348
Owners-Override: Pavol Marko <pmarko@chromium.org>
Auto-Submit: Pavol Marko <pmarko@chromium.org>
Reviewed-by: Maria Petrisor <mpetrisor@chromium.org>
Commit-Queue: Maria Petrisor <mpetrisor@chromium.org>
Reviewed-by: Denis Kuznetsov <antrim@chromium.org>
Commit-Queue: Denis Kuznetsov <antrim@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#987871}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3582336
Auto-Submit: Sven Zheng <svenzheng@chromium.org>
Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/branch-heads/4951@{#741}
Cr-Branched-From: 27de622-refs/heads/main@{#982481}

testing/buildbot/chromium.chromiumos.json

@@ -2452,7 +2452,7 @@
             }
           ],
           "service_account": "chromium-tester@chops-service-accounts.iam.gserviceaccount.com",
-          "shards": 3
+          "shards": 6
         },
         "test": "interactive_ui_tests",
         "test_id_prefix": "ninja://chrome/test:interactive_ui_tests/"

testing/buildbot/test_suite_exceptions.pyl

@@ -1992,6 +1992,11 @@
           'shards': 10,
         },
       },
+      'linux-chromeos-dbg': {
+        'swarming': {
+          'shards': 6,
+        },
+      },
       'linux-code-coverage': {
         'swarming': {
           'shards': 10,