Remove unused methods in integrations

We stopped using these methods when we made some changes to the Jira
form in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/30258

app/models/integration.rb

@@ -183,10 +183,6 @@ class Integration < ApplicationRecord
     self.supported_events.map { |event| IntegrationsHelper.integration_event_field_name(event) }
   end
 
-  def self.supported_event_actions
-    %w[]
-  end
-
   def self.supported_events
     %w[commit push tag_push issue confidential_issue merge_request wiki_page]
   end
@@ -473,10 +469,6 @@ class Integration < ApplicationRecord
     end
   end
 
-  def configurable_event_actions
-    self.class.supported_event_actions
-  end
-
   def supported_events
     self.class.supported_events
   end

app/models/integrations/jira.rb

@@ -47,10 +47,6 @@ module Integrations
       %w(commit merge_request)
     end
 
-    def self.supported_event_actions
-      %w(comment)
-    end
-
     # {PROJECT-KEY}-{NUMBER} Examples: JIRA-1, PROJECT-1
     def self.reference_pattern(only_long: true)
       @reference_pattern ||= /(?<issue>\b#{Gitlab::Regex.jira_issue_key_regex})/

app/models/integrations/zentao.rb

@@ -48,10 +48,6 @@ module Integrations
       %w()
     end
 
-    def self.supported_event_actions
-      %w()
-    end
-
     def fields
       [
         {