Use number formatting (e.g. thousands separator) in the total runners
Description
The runner's totals should have a number formatting that corresponds to the language used. See #344857 (comment 749284674)
The number is being formatted in https://gitlab.com/gitlab-org/gitlab/blob/14ab76f95e016a638e756cfb3a6989fef0a9fb33/app/helpers/ci/runners_helper.rb#L71
Currently
Expected
143,385 (in en-US locale)