Duration of each step could be displayed

While https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/issues/2412 is implemented, a first easy step could be to just display the duration for each step:

For instance:

Fetching changes for 33600-fix-uncaught-throw-in-ee_compat_check with git depth set to 20...
HEAD is now at ff97afd Merge branch '33461-display-user-id' into 'master'
From https://gitlab.com/gitlab-org/gitlab-ce
* [new branch] 33600-fix-uncaught-throw-in-ee_compat_check -> origin/33600-fix-uncaught-throw-in-ee_compat_check
Checking out d9a92218 as 33600-fix-uncaught-throw-in-ee_compat_check...
Checking out d9a92218 as 33600-fix-uncaught-throw-in-ee_compat_check... > Done in 32 seconds
Skipping Git submodules setup
Skipping Git submodules setup > Done in 1 seconds
Checking cache for ee_compat_check_repo...
Checking cache for ee_compat_check_repo... > Done in 349 seconds

The duration is shown as Description of the step > Done in X seconds here.

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This would allow to at least understand what are the steps that take most of the time for each job.