chore: Remove unused attribute imap_inbox_synced_at (#8822)

- imap_inbox_synced_at is no longer used; this PR removes all the references to the same.

app/javascript/dashboard/routes/dashboard/settings/inbox/ImapSettings.vue

@@ -143,9 +143,6 @@ export default {
             imap_login: this.login,
             imap_password: this.password,
             imap_enable_ssl: this.isSSLEnabled,
-            imap_inbox_synced_at: this.isIMAPEnabled
-              ? new Date().toISOString()
-              : undefined,
           },
         };
 

app/models/channel/email.rb

@@ -8,7 +8,6 @@
 #  imap_address              :string           default("")
 #  imap_enable_ssl           :boolean          default(TRUE)
 #  imap_enabled              :boolean          default(FALSE)
-#  imap_inbox_synced_at      :datetime
 #  imap_login                :string           default("")
 #  imap_password             :string           default("")
 #  imap_port                 :integer          default(0)
@@ -41,7 +40,7 @@ class Channel::Email < ApplicationRecord
   AUTHORIZATION_ERROR_THRESHOLD = 10
 
   self.table_name = 'channel_email'
-  EDITABLE_ATTRS = [:email, :imap_enabled, :imap_login, :imap_password, :imap_address, :imap_port, :imap_enable_ssl, :imap_inbox_synced_at,
+  EDITABLE_ATTRS = [:email, :imap_enabled, :imap_login, :imap_password, :imap_address, :imap_port, :imap_enable_ssl,
                     :smtp_enabled, :smtp_login, :smtp_password, :smtp_address, :smtp_port, :smtp_domain, :smtp_enable_starttls_auto,
                     :smtp_enable_ssl_tls, :smtp_openssl_verify_mode, :smtp_authentication, :provider].freeze