[NTP] Fix field trial config for CerseiFakeboxOnNtp.

Updated field trial config to separate features into the individual groups
that are used in the study. This should resolve issues raised by Finch
analyzers.

Bug: 956164,956613
Change-Id: I7b07f0cab091f39aed7bd9ecce17126322c81287
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1612257Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Ramya Nagarajan <ramyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659707}

testing/variations/fieldtrial_testing_config.json

@@ -1315,14 +1315,48 @@
             ],
             "experiments": [
                 {
-                    "name": "CerseiFakeboxOnNtp",
+                    "name": "EnabledAlt",
+                    "enable_features": [
+                        "UseAlternateFakeboxOnNtp"
+                    ]
+                },
+                {
+                    "name": "EnabledAltWithIcon",
+                    "enable_features": [
+                        "FakeboxSearchIconOnNtp"
+                    ]
+                },
+                {
+                    "name": "EnabledAltWithIconColor",
+                    "enable_features": [
+                        "FakeboxSearchIconColorOnNtp"
+                    ]
+                },
+                {
+                    "name": "EnabledAltRect",
+                    "enable_features": [
+                        "UseAlternateFakeboxRectOnNtp"
+                    ]
+                },
+                {
+                    "name": "EnabledAltRectWithIcon",
                     "enable_features": [
-                        "FakeboxSearchIconColorOnNtp",
                         "FakeboxSearchIconOnNtp",
-                        "FakeboxShortHintTextOnNtp",
-                        "UseAlternateFakeboxOnNtp",
                         "UseAlternateFakeboxRectOnNtp"
                     ]
+                },
+                {
+                    "name": "EnabledAltRectWithIconColor",
+                    "enable_features": [
+                        "FakeboxSearchIconColorOnNtp",
+                        "UseAlternateFakeboxRectOnNtp"
+                    ]
+                },
+                {
+                    "name": "EnabledShortString",
+                    "enable_features": [
+                        "FakeboxShortHintTextOnNtp"
+                    ]
                 }
             ]
         }