Remove Attributes column from Inherited CI/CD Variables table

What does this MR do and why?

This column was removed from the Project CI/CD Variables table, but not the table for inherited group variables. We don't need to show this column anymore since we already render the attributes as labels under the variable key.

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Screenshots or screen recordings

Before	After

For reference, this is how the project variables table looks like. We do not show the value or actions column for inherited variables.

How to set up and validate locally

1. Use this rake task to add group variables for your group.

   bundle exec rake "gitlab:seed:ci_variables_group[<group_name>, 5]"

2. Visit the CI/CD settings of a project under the group: /path-to-project/-/settings/ci_cd
3. Scroll to Variables > Group variables (inherited) (it's another table under the project variables table) and verify that the Attributes column is no longer there.