Follow-up from "Emphasize highlights that have vulnerabilities"

The following discussion from !163719 (merged) should be addressed:

• @dftian started a discussion:

  (optional) Unrelated to this MR, but the '1000+' string isn't localized, so it won't work well for East Asian languages (which uses a monospace + character) and RTL languages (which shows '+1000').

  If it's highly unlikely that SEVERITY_COUNT_LIMIT will change to something besides 1000, we already have a __('1000+') localization that we can use here. Otherwise, maybe we can introduce a __('%{count}+') localization.