fix ssh config parsing for HostName

[kila-star1127]

A later invocation to url.Parse() needs a preceding scheme, otherwise the hostname just gets discarded.

Fixes #25067

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This is a re-submission of #27673 (authored by @Jannik2099)

The original PR is stalled due to the addition of tests.

The maintainers (@mheon, @giuseppe) agreed to merge without tests, but @mtrmac expressed concerns about the test content.

Since it was deemed acceptable to merge without tests, I removed them.

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Does this PR introduce a user-facing change?

Fix podman-remote being unable to connect to any host with a custom HostName in the user's ~/.ssh/config