Addressing the workspaces cert variables as file type

What does this MR do and why?

As a follow up on MR !123454 (merged) and https://gitlab.com/gitlab-org/quality/engineering-productivity-infrastructure/-/merge_requests/436, there were few variables that needed to be changed to file type in MR - https://gitlab.com/gitlab-org/quality/engineering-productivity-infrastructure/-/merge_requests/445. So addressing the code to refer these variables as file type.

Screenshots or screen recordings

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Before	After

How to set up and validate locally

The full list of variable and their values to run this spec can be found in 1password "Run workspaces tests against staging"

bundle exec bin/qa Test::Instance::All https://staging.gitlab.com -- -- qa/specs/features/ee/browser_ui/3_create/remote_development/workspace_actions_spec.rb

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.