[api] Make jobhistory_list a class method

Because we are not using the instance attributes.

src/api/app/controllers/webui/packages/job_history_controller.rb

@@ -7,7 +7,7 @@ class JobHistoryController < WebuiController
       before_action :set_architecture
 
       def index
-        @jobshistory = @package.jobhistory_list(@project.name, @repository.name, @architecture.name, @package_name)
+        @jobshistory = Package.jobhistory_list(@project.name, @repository.name, @architecture.name, @package_name)
       end
 
       private

src/api/app/models/package.rb

@@ -914,7 +914,7 @@ def buildresult(prj = project, show_all = false)
     LocalBuildResult::ForPackage.new(package: self, project: prj, show_all: show_all)
   end
 
-  def jobhistory_list(project_name, repository_name, arch_name, package_name)
+  def self.jobhistory_list(project_name, repository_name, arch_name, package_name)
     begin
       results = Xmlhash.parse(Backend::Api::BuildResults::JobHistory.all_for_package(project_name, package_name, repository_name, arch_name))
     rescue Backend::Error

src/api/spec/models/package_spec.rb

@@ -433,11 +433,11 @@
     end
   end
 
-  describe '#jobhistory_list' do
+  describe '.jobhistory_list' do
     let(:backend_url) { "#{CONFIG['source_url']}/build/#{home_project}/openSUSE_Tumbleweed/x86_64/_jobhistory?limit=100&package=#{package}" }
 
     # the package name is needed because it could be a multibuild
-    subject { package.jobhistory_list(home_project, 'openSUSE_Tumbleweed', 'x86_64', package.name) }
+    subject { Package.jobhistory_list(home_project, 'openSUSE_Tumbleweed', 'x86_64', package.name) }
 
     context 'when response is successful' do
       let(:local_job_history) do