Add linux_chromium_clobber_rel_ng as a 10% experiment.

testing/commit_queue/config.json

 {
     "experimental_tryjobs": {
         "10 percent experiment": {
             "percentage": 0.1,
             "trybots": {
                 "launched": {
                     "tryserver.chromium.linux": {
                         "cast_shell": ["defaulttests"],
                         "cast_shell_apk": ["defaulttests"],
                         "linux_android_rel_ng": ["defaulttests"],
-                        "linux_chromium_asan_rel_ng": ["defaulttests"]
+                        "linux_chromium_asan_rel_ng": ["defaulttests"],
+                        "linux_chromium_clobber_rel_ng": ["defaulttests"]
                     },
                     "tryserver.chromium.mac": {
                         "mac_chromium_gn_rel": ["defaulttests"]
                     },
                     "tryserver.chromium.win": {
                         "win8_chromium_ng": ["defaulttests"],
                         "win8_chromium_gn_rel": ["defaulttests"]
                     }
                 }
             }
@@ skipping 69 matching lines @@
               "win8_chromium_rel": ["defaulttests"],
               "win_chromium_compile_dbg_ng": ["defaulttests"],
               "win_chromium_rel_ng": ["defaulttests"],
               "win_chromium_x64_rel_ng": ["defaulttests"]
             }
         },
         "triggered": {
         }
     }
 }