Revert explore projects default sort to last updated

What does this MR do?

Revert explore projects default sort to last updated. Partial revert of !47734 (merged)

Does not affect https://gitlab.com/dashboard/projects

Why ?

https://gitlab.com/explore/projects is being gamed:

The problem we are fixing is for non-logged in users and Googlebot going to https://gitlab.com/explore/projects. They should not see the same list of projects always.

Screenshots (strongly suggested)

Screenshot with fix, viewing as non-logged in user:

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done