Update masked value styling

Summary

Update masked values in the CI/CD variable areas:

• Project Settings > CI/CD > Variables
• Group Settings > CI/CD > Variables
• Admin area > Settings > CI/CD > Variables

Note These settings all use the same table

More context: #432384[Edit_Secret.png] (comment 2336422163)

Definition of Done

Current	Proposed change

• Update characters * to • when the values are masked.

Roles involved

• Design
• Technical Writing
• Backend
• Frontend
• Test engineering

NOTE: When work is ready to be defined, please create appropriate sub-tasks.