Fix Style/IfUnlessModifier offences

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What does this MR do and why?

Fixing offences for -

    - 'app/helpers/admin/user_actions_helper.rb'
    - 'app/helpers/blob_helper.rb'
    - 'app/helpers/button_helper.rb'
    - 'app/helpers/ci/status_helper.rb'
    - 'app/helpers/diff_helper.rb'
    - 'app/helpers/emails_helper.rb'
    - 'app/helpers/events_helper.rb'
    - 'app/helpers/form_helper.rb'
    - 'app/helpers/groups_helper.rb'
    - 'app/helpers/lazy_image_tag_helper.rb'

Mentioning that the name of branch has to be - 39356-fix-Style/IfUnlessModifier

Related to #239356