[Simplified NTP] Update fieldtrial testing config

Update fieldtrial testing config for experiment with scroll-to-load
disabled.

BUG=

Change-Id: Ibb8c76592c12addd3c2f807fe9d338665f30e0c0
Reviewed-on: https://chromium-review.googlesource.com/1110850
Commit-Queue: Theresa <twellington@chromium.org>
Commit-Queue: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569411}

testing/variations/fieldtrial_testing_config.json

@@ -3755,18 +3755,24 @@
             ],
             "experiments": [
                 {
-                    "name": "Enabled",
+                    "name": "Enabled_NoScrollToLoad",
                     "enable_features": [
                         "SimplifiedNTP"
+                    ],
+                    "disable_features": [
+                        "ContentSuggestionsScrollToLoad"
                     ]
                 },
                 {
-                    "name": "Enabled_Ablation",
+                    "name": "Enabled_Ablation_NoScrollToLoad",
                     "params": {
                         "simplified_ntp_ablation": "true"
                     },
                     "enable_features": [
                         "SimplifiedNTP"
+                    ],
+                    "disable_features": [
+                        "ContentSuggestionsScrollToLoad"
                     ]
                 }
             ]