Correct git protocol v2 tests

What does this MR do?

• Git protocol v2 tests began to fail because Result now returns a struct object instead of a string object
• Tests will now examine the headers during the handshake process which, by specification, are guaranteed to advertise protocol version

What are the relevant issue numbers?

Resolves charts/gitlab#1052

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer

Closes charts/gitlab#1052