Fix ordering of commits in the network graph.

What does this MR do?

• We upgraded rugged to 0.25.1.1 in !10286 (merged) for %9.1

• Prior to this upgrade, the default sort order for commits returned by Gitlab::Git::Repository#find_commits was Rugged::SORT_DATE, which the graph relied on.

• While upgrading rugged, the MR also changed this default to Rugged::SORT_NONE, which broke commit ordering in the graph.

• This MR adds an option to Gitlab::Git::Repository#find_commits to sort by date, and changes the graph builder Network::Graph so it explictly requests the :date sort order

What are the relevant issue numbers?

Closes #30973 (closed)

Tasks

• Investigation
• Implementation
• Tests
  • Added
    • Add more tests for Network::Graph
    • Compare results of this fix v/s 9.0 and confirm that there are no changes
  • Passing
• Meta
  • CHANGELOG entry created
  • API support added
  • Branch has no merge conflicts with master
  • Squashed related commits together
  • Added screenshots
  • Check for clean merge with EE
  • Documentation added/updated
• Review
  • Reviewer
  • Maintainer
• Wait for merge