Improve copy for the pending state

app/views/projects/jobs/show.html.haml

@@ -106,7 +106,7 @@
         illustration: 'illustrations/job_not_triggered.svg',
         illustration_size: 'svg-306',
         title: _('This job has not started yet'),
-        content: _('This job is in pending state and is waiting to be picked by the runner')
+        content: _('This job is in pending state and is waiting to be picked by a runner')
   = render "sidebar"
 .js-build-options{ data: javascript_build_options }

spec/features/projects/jobs_spec.rb

@@ -389,7 +389,7 @@ feature 'Jobs' do
         wait_for_requests
         expect(page).to have_content('This job has not started yet')
-        expect(page).to have_content('This job is in pending state and is waiting to be picked by the runner')
+        expect(page).to have_content('This job is in pending state and is waiting to be picked by a runner')
         expect(page).to have_content('pending')
       end
     end
@@ -416,7 +416,7 @@ feature 'Jobs' do
       it 'shows pending empty state' do
         expect(page).to have_content('This job has not started yet')
-        expect(page).to have_content('This job is in pending state and is waiting to be picked by the runner')
+        expect(page).to have_content('This job is in pending state and is waiting to be picked by a runner')
       end
     end
   end