Refactor FXIOS [Nimbus] Update initial experiments JSON for Nimbus (backport #29397) (#29405)

* Refactor FXIOS [Nimbus] Update initial experiments JSON for Nimbus (#29397)

update initial_experiments.json based on the current first-run experiments in experimenter

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
(cherry picked from commit aa19193)

# Conflicts:
#	firefox-ios/Client/Experiments/initial_experiments.json

* fix: conflict

* chore: remove apple

* chore: revert search change

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Issam Mani <[email protected]>

Author: 3 people

firefox-ios/Client/Experiments/initial_experiments.json

@@ -556,26 +556,26 @@
     },
     {
       "schemaVersion": "1.12.0",
-      "slug": "summarizer-apple-intelligence-rollout-beta-test",
-      "id": "summarizer-apple-intelligence-rollout-beta-test",
+      "slug": "summarizer-mistral-model-rollout-first-run-new-users",
+      "id": "summarizer-mistral-model-rollout-first-run-new-users",
       "arguments": {},
       "application": "org.mozilla.ios.Firefox",
       "appName": "firefox_ios",
       "appId": "org.mozilla.ios.Firefox",
       "channel": "release",
-      "userFacingName": "Summarizer - Apple Intelligence Full Release Rollout",
+      "userFacingName": "Summarizer - Mistral Model Rollout First Run New Users",
       "userFacingDescription": "Summarizer",
       "isEnrollmentPaused": false,
       "isRollout": true,
       "bucketConfig": {
         "randomizationUnit": "nimbus_id",
-        "namespace": "ios-apple-summarizer-feature-release-no_targeting-rollout-1",
+        "namespace": "ios-hosted-summarizer-feature-release-mobile_new_users-rollout-2",
         "start": 0,
         "count": 10000,
         "total": 10000
       },
       "featureIds": [
-        "apple-summarizer-feature"
+        "hosted-summarizer-feature"
       ],
       "probeSets": [],
       "outcomes": [],
@@ -590,7 +590,7 @@
           },
           "features": [
             {
-              "featureId": "apple-summarizer-feature",
+              "featureId": "hosted-summarizer-feature",
               "enabled": true,
               "value": {
                 "enabled": true,
@@ -601,17 +601,17 @@
           ]
         }
       ],
-      "targeting": "(app_version|versionCompare('143.!') >= 0) && (language in ['en'])",
-      "startDate": "2025-09-11",
+      "targeting": "((is_already_enrolled) || ((days_since_install < 7) && (app_version|versionCompare('143.!') >= 0) && (language in ['en']) && (region in ['US']) && (('summarizer-mistral-model-full-rollout' in enrollments) == false) && ((enrollments_map['summarizer-mistral-model-rollout'] == 'treatment-a') == false)))",
+      "startDate": "2025-09-17",
       "enrollmentEndDate": null,
       "endDate": null,
       "proposedDuration": 28,
-      "proposedEnrollment": 7,
+      "proposedEnrollment": 14,
       "referenceBranch": "control",
       "featureValidationOptOut": false,
       "localizations": null,
       "locales": null,
-      "publishedDate": "2025-09-11T16:58:59.108457Z",
+      "publishedDate": "2025-09-17T19:20:28.247535Z",
       "isFirefoxLabsOptIn": false,
       "firefoxLabsTitle": "",
       "firefoxLabsDescription": "",