Align UI to use "Duration" for CI/CD job page

Updates the text on the jobs page so that we use clear
language to talk about the time it takes a job to run.

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

@@ -28,7 +28,7 @@
             %th Runner
           %th Stage
           %th Name
-          %th Timing
+          %th Duration
           %th Coverage
           %th
 

changelogs/unreleased/ui-text-job-pipeline-runtime.yml

+---
+title: Update UI text from timing to Run time
+merge_request: 58838
+author:
+type: other