fix: Skip email rate limiting for self-hosted instances (#13915)

Self-hosted installations were incorrectly hitting the daily email rate
limit of 100, seeded from `installation_config`. Since self-hosted users
control their own infrastructure, email rate limiting should only apply
to Chatwoot Cloud.

Closes #13913

app/models/concerns/account_email_rate_limitable.rb

@@ -17,6 +17,7 @@ module AccountEmailRateLimitable
   end
 
   def within_email_rate_limit?
+    return true unless ChatwootApp.chatwoot_cloud?
     return true if emails_sent_today < email_rate_limit
 
     Rails.logger.warn("Account #{id} reached daily email rate limit of #{email_rate_limit}. Sent: #{emails_sent_today}")