PlzNavigate: increse max retries for our FYI bot.

testing/buildbot/chromium.fyi.json

 {
   "Android Cloud Tests": {
     "gtest_tests": [
       {
         "test": "android_webview_unittests"
       },
       {
         "test": "base_unittests"
       },
       {
@@ skipping 161 matching lines @@
       {
         "test": "webkit_unit_tests"
       }
     ]
   },
   "Browser Side Navigation Linux": {
     "gtest_tests": [
       {
         "args": [
           "--enable-browser-side-navigation",
-          "--test-launcher-filter-file=src/testing/buildbot/filters/browser-side-navigation.linux.browser_tests.filter"
+          "--test-launcher-filter-file=src/testing/buildbot/filters/browser-side-navigation.linux.browser_tests.filter",
+          "--test-launcher-retry-limit=6"
         ],
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "browser_tests"
       },
       {
         "args": [
           "--enable-browser-side-navigation",
           "--test-launcher-filter-file=src/testing/buildbot/filters/browser-side-navigation.linux.content_browsertests.filter"
@@ skipping 5616 matching lines @@
       },
       {
         "args": [
           "--isolate-extensions"
         ],
         "test": "unit_tests"
       }
     ]
   }
 }