[Android] Raise chrome_public_test_apk timeout on chromium.linux:Android Tests (dbg).

testing/buildbot/chromium.linux.json

 {
   "Android Arm64 Builder (dbg)": {
     "additional_compile_targets": [
       "all"
     ]
   },
   "Android Builder": {
     "additional_compile_targets": [
       "cronet_test_instrumentation_apk",
       "system_webview_apk"
@@ skipping 1547 matching lines @@
               "revision": "git_revision:ff387eadf445b24c935f1cf7d6ddd279f8a6b04c"
             }
           ],
           "dimension_sets": [
             {
               "android_devices": "6",
               "device_os": "KTU84P",
               "device_type": "hammerhead"
             }
           ],
-          "hard_timeout": 1800,
+          "hard_timeout": 2400,
           "output_links": [
             {
               "link": [
                 "https://luci-logdog.appspot.com/v/?s",
                 "=android%2Fswarming%2Flogcats%2F",
                 "${TASK_ID}%2F%2B%2Funified_logcats"
               ],
               "name": "shard #${SHARD_INDEX} logcats"
             }
           ]
@@ skipping 3074 matching lines @@
         "isolate_name": "telemetry_unittests",
         "name": "telemetry_unittests",
         "swarming": {
           "can_use_on_swarming_builders": true,
           "shards": 4
         }
       }
     ]
   }
 }