chore: improve plan-based feature handling with plan hierarchy (#11335)

- Refactor HandleStripeEventService to better manage features by plan
- Add constants for features available in each plan tier (Startup,
Business, Enterprise)
- Add channel_instagram to Startup plan features
- Improve downgrade handling to properly disable higher-tier features
- Clean up and optimize tests for maintainability
- Add comprehensive test coverage for plan upgrades and downgrades

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Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

enterprise/app/jobs/internal/account_analysis_job.rb

@@ -2,7 +2,7 @@ class Internal::AccountAnalysisJob < ApplicationJob
   queue_as :low
 
   def perform(account)
-    return if GlobalConfig.get_value('DEPLOYMENT_ENV') != 'cloud'
+    return unless ChatwootApp.chatwoot_cloud?
 
     Internal::AccountAnalysis::ThreatAnalyserService.new(account).perform
   end