Fix last update time for project in group page

What does this MR do and why?

Closes: #349310 (closed)

Relative issue:

• gitlab-foss#56227 (closed)
• #25862 (closed)

Screenshots or screen recordings

How to set up and validate locally

In GDK environment:

1. Create a Group on the group page.
2. Create a Project in your new Group.
3. Wait for a moment, then push a commit to your new Project.
4. Compare with Group page and Project dashboard page last update time.

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.

Related to #349310 (closed)