Display "Hours remaining until termination" on Workspace list

Issue: Display "Hours remaining until termination" on ... (#467319 - closed)

What does this MR do and why?

The Workspace list should display a column "Terminates" for each non-terminated workspace, representing the number of hours (rounded down) until the workspace auto-terminates.

NOTE: This issue represents part of the request from Workspace termination warning in IDE (#467093) - it displays the time until termination, but does not display any warning in the IDE.

Acceptance Criteria

• "Terminates" field displays correctly calculated numbers
• Field is not displayed for terminated workspaces.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

How to set up and validate locally

• Create workspaces with various termination timeouts, verify that the value shown for them on the list is correct.