[NTP] Add field trial config for CerseiFakeboxOnNtp

Add field trial config for next round of alternate fakebox variations
on the NTP. This replaces the UseAlternateFakeboxOnNtp experiment.

Bug: 956164,956613
Change-Id: I1ae572142dc1d492371c5559838fb1a4bf5b28dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1600159Reviewed-by: Ramya Nagarajan <ramyan@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Kristi Park <kristipark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658286}

testing/variations/fieldtrial_testing_config.json

@@ -1286,6 +1286,28 @@
             ]
         }
     ],
+    "CerseiFakeboxOnNtp": [
+        {
+            "platforms": [
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "CerseiFakeboxOnNtp",
+                    "enable_features": [
+                        "FakeboxSearchIconColorOnNtp",
+                        "FakeboxSearchIconOnNtp",
+                        "FakeboxShortHintTextOnNtp",
+                        "UseAlternateFakeboxOnNtp",
+                        "UseAlternateFakeboxRectOnNtp"
+                    ]
+                }
+            ]
+        }
+    ],
     "CertDualVerificationTrial": [
         {
             "platforms": [
@@ -5234,25 +5256,6 @@
             ]
         }
     ],
-    "UseAlternateFakeboxOnNtp": [
-        {
-            "platforms": [
-                "chromeos",
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "UseAlternateFakeboxOnNtp",
-                    "enable_features": [
-                        "FakeboxSearchIconOnNtp",
-                        "UseAlternateFakeboxOnNtp"
-                    ]
-                }
-            ]
-        }
-    ],
     "UseFluentLanguageModel": [
         {
             "platforms": [