Remove Jira tracker unused code

app/models/project.rb

@@ -1292,10 +1292,6 @@ class Project < ApplicationRecord
     @monitoring_service ||= monitoring_services.reorder(nil).find_by(active: true)
   end
 
-  def jira_tracker?
-    issues_tracker.to_param == 'jira'
-  end
-
   def avatar_in_git
     repository.avatar
   end
@@ -1604,10 +1600,6 @@ class Project < ApplicationRecord
     end
   end
 
-  def jira_tracker_active?
-    jira_tracker? && jira_service.active
-  end
-
   def allowed_to_share_with_group?
     !namespace.share_with_group_lock
   end

ee/app/models/ee/project.rb

@@ -406,10 +406,6 @@ module EE
       super && !(group && ::Gitlab::CurrentSettings.lock_memberships_to_ldap?)
     end
 
-    def reference_issue_tracker?
-      default_issues_tracker? || jira_tracker_active?
-    end
-
     # TODO: Clean up this method in the https://gitlab.com/gitlab-org/gitlab/issues/33329
     def approvals_before_merge
       return 0 unless feature_available?(:merge_request_approvers)