Update CI/CD variables table to show more data

This MR is a part of the ✨ Beautifying our UI (15.5) ✨ 

What does this MR do and why?

This MR changes the table view of the CI/CD variables to make the variable key and environment visible for users. The changes contain:

• Allow columns to wrap instead of truncating
• Shorten the value column to 5 asterisks
• Merge protected, masked into one column options
• Allow copying cell value without triggering a popover

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Go to Project -> Settings -> CI/CD and select Variables section.
2. Create some variables to validate the table view.
3. As the MR introduces changes for both legacy and new variable tables, to validate the new one, turn on the ci_variable_settings_graphql feature flag.

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.

Review progress:

• UX review
• frontend developer review
• frontend maintainer review

Related to #374580 (closed) and #375203 (closed)