fix parsing of RHSM proxy configuration (#10060)

[tmurakam]

Remove URL scheme part from http_proxy for server.proxy_hostname

What type of PR is this?

/kind bug

What this PR does / why we need it:

Fix bug #10060 to make redhat suscription manager (RHSM) works properly under proxy environment.

Which issue(s) this PR fixes:

Fixes #10060

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Fix parsing of RHSM proxy configuration

[k8s-ci-robot]

Hi @tmurakam. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[MrFreezeex]

Thanks for your contributions, looks good 👍!
/lgtm
/ok-to-test

[floryut]

@tmurakam Thank you for the PR 👍
/kind Feature
/ok-to-test

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: floryut, MrFreezeex, tmurakam

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