Avoid resource intensive login checks if password is not provided

What does this MR do?

Skip checks of user/password validity for git http calls when password is nil/empty.

Why was this MR needed?

Avoid unnecessary resource intensive calls against DB or external systems (i.e. LDAP)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

#32598 (closed)